Palo Duro Consulting

Antibiotic Feed Ban?

2005-07-12T14:01:00.000-07:00

I graduated from veterinary school in 1965 and one of the first seminars I attended was on antibiotic drug resistance with the idea of banning the use of antibiotics in livestock feed. Today (2005) forty years later, the U. S. Food and Drug Administration (FDA) faces regulatory petition to ban antibiotics in the feed. Why? Are the proposed regulations politically motivated and unnecessary? Science versus politics?

The Preservation of Antibiotics for Medical Treatment Act of 2005 was reintroduced in the Senate with a House companion expected to follow. Sponsored by Senator’s Olympia Snowe and Edward Kennedy, the bill would phase out non-therapeutic use of antibiotics in feed over two years unless manufactures adequately demonstrate that specific drug uses do not promote resistance in humans. The petition and legislation targets penicillins, tetracyclines, macrolides, lincosamides, streptomycins, aminoglycosides, and sulfonamides. Since 1965, this issue has been proposed and scientific data has been presented to no avail. Science versus politics?

The Animal Health Institute (AHI) state “ Scientific evidence, including government monitoring and surveillance data, demonstrates the careful use of antibiotics in food animals has public health benefits that far out weigh the very small risks.” “ We oppose these misguided efforts and will continue to work to ensure the proper and careful use of antibiotics to keep food animals healthy and contribute to public health through the provision of a safe supply of meat, milk and eggs.”

As recent as October 2003, FDA’s use of Guidance #152 establishes safety criteria for evaluating antimicrobial drugs with regard to microbiological effects on bacteria and human health concerns. This establishes if there is a valid risk assessment done that show’s a significant problem, FDA has the power to deal with it. American Association of Bovine Practitioner’s (AABP) Executive Director, Dr. Gatz Riddell states, “ advocacy groups are blatantly against antimicrobials in production animals and this political pressure is based on distorted facts.”

I stay confused on this issue.

In the April 15 issue of the Morbidity and Mortality Weekly Report (MMWR), which is published by the National Centers for Disease Control and Prevention, reports that food borne infections caused by several bacterial pathogens are on the decline. The MMWR describes preliminary surveillance data for 2004 and compares them with baseline data gathered from 1996-1998.

The report states that the estimated incidence of infection with Campylobacter decreased 31 %, Crytosporidium and Listeria decreased 40 %, Shigatoxin producing Escherichia coli 0157 decreased 42 % and overall Salmonella infections decreased 8 %.

Although Salmonella incidence decreased overall, of the most common Salmonella serotypes, only the incidence of S. typhimurium decreased significantly, 41 %.

“Dramatic multiyear reductions in illnesses from E. coli 0157 mean the U. S. is now below Healthy People 2010 goal of 1.0 case per 100,000 persons. This is a remarkable national achievement, “ said Merle Pierson, PhD, USDA acting under secretary for food safety. “ We are also very close to meeting the Healthy People 2010 goal set for illness from Listeria monocytogenes and Camplobacter.”

The reductions in illnesses have occurred concurrently with several important food safety initiatives and educational efforts. (Not withdrawal of antibiotics) Multiple interventions that might have contributed to this decline include industry response to the FSIS 2002 notice to manufactures to reassess control strategies for STEC 0157 in the production of ground beef. Enhanced strategies for reducing pathogens in live cattle and during slaughter may have also played a role.

References:

DVM Magazine; May 2005; Exclusive News

JAVMA Vol 226, No 11, News/Public Health

Electronic Identification of Cattle

2004-12-23T14:00:00.000-08:00

This author is not trying to get into the debate of promoting an animal identification plan but to provide information or location where more information can be obtained about such a plan.

U.S Agriculture Secretary Ann M. Veneman stated “All of these animal health issues point to the importance of the development of a National Animal Identification System, which is a key priority for USDA… Together, we must develop a system that works.”

The United States Animal Health Association (USAHA) has endorsed a plan to implement a national system for animal identification as a work in progress.

The U.S. animal Identification Plan (USAIP), as it is called, defines the standards and framework for implementing a phased-in national food animal and livestock identification program.

The National Animal Identification Development Team that was comprised of a diverse group of livestock industry participants including producers, producer’s organizations, breed associations, marketers, processors, and state, federal animal health officials were given the task to develop a system to assist in rapid animal traceback in the event of an animal health emergency.

To stay informed of the rapidly changing proposal and the implementation of a USAIP plan, producers and others with interests in the industry are encouraged to use http://www.usaip.info/. Many of the rules and details of the proposed plan will become more evident as it moves through the political process.

Another source of information can be obtained from Electronic ID, A User’s Manual published by Beef, December 2003.

This issue of Beef was solely dedicated to examining animal identification (ID) using radio-frequency identification (RFID) technology. It was designed to add to the industry awareness of animal traceback in general and RFID technology specifically. The RFID technology appears to have the inside track to become the foundation of such a traceback system.

The December 2003 issue included articles detailing the technology, its providers, the specifications, and to help the livestock producers evaluate and understand electronic ID.

Kansas State University in cooperation with Beef magazine did an extensive survey of the products and services offered by various companies in the animal identification business. These results may be found at http://www.beefstockerusa.org/.

A Guide for Electronic Identification of Cattle produced by Kansas State University Agriculture Experiment Station and Cooperative Extension Service is an excellent publication providing an overview of radio frequency technology and its application in a national identification program for the beef industry.

Establishing common data sharing standards is becoming critical to the future of the segmented beef industry. A collation of five leading agriculture data service companies have announced plans to create this industry’s first data exchange standards.

The five participating companies:

AgInfoLink USA, Longmont, Colorado
APEIS Corporation, Norfolk, Nebraska
Emerge Interactive, Inc., Sebastian, Florida
IMI Global, Inc., Platte City, Missouri, and
Micro Beef Technologies, Ltd., Amarillo, Texas are establishing the Beef Information Exchange to address the need for a uniform set of data movement standards among the nation’s beef industry producers.

Initially, the Beef Information Exchange will facilitate rapid and secure sharing of data required for a national identification system to address potential mandatory identification and traceback requirements. The system may be expanded to accommodate a greater variety of production data. Establishing common data-sharing standards creates a standard information platform, which will allow for greater operational efficiency, reduced supply uncertainties, and potentially lower costs.

The time has come to learn more about an animal identification plan and make it work in our segmented industry.

References:

1. Cattle Health Report
A National Institute for Animal Agriculture Publication

2. A Guide for Electronic Identification of Cattle.

Kansas State University Agricultural Experiment Station and Cooperative Extension Service

3. Electronic ID: A User’s Manual

Beef Magazine, December 2003

4. Beef Production Medicine 2004

Implants and thier Use in the Feedyard

2004-09-20T13:59:00.000-07:00

Most procedures performed during the processing of feeder cattle are geared toward the prevention of problems and, therefore, economic savings. However, implanting gives a direct enhancement of performance and, therefore, economic gain.

When administered properly, implants make money for the cattle feeder. It is estimated that an implant provides a return on investment anywhere from 10:1 to 20:1. That variation is due to such factors as market price, size, weight and genetic potential of the feeder animal, and type of ration.

In any case, implanting feeder cattle is a sound economic practice that should be performed for financial gain.

Implants act to improve feed efficiency (pounds of feed required to produce a pound of gain in body weight) and rate of gain (pounds of body weight gained per day).

They are considered to be anabolic agents, enhancing protein metabolism and muscle production in the animal. Though the mechanism of action is not yet completely understood, it is felt that these agents regulate naturally produced compounds in the body to enhance growth and muscle production. In effect, they may stimulate a more consistent daily production level of these compounds, as they tend to be erratic by nature.

Our industry faces a continuing challenge to educate the consumer as to the wholesomeness and safety of our product. Public concern about implanted beef plus the concept and promotion of “natural” beef-have clouded the realistic picture.

These concerns are unjustified and the issue is one of public relations and education, rather than one of health.

Consider these facts: 168 pounds of implanted beef contains the same amount of estrogen as one egg. Four ounces of beef contain 1.59 nanograms (1 billionth of a gram) of estrogen. An adult man averages 130,000 nanograms of estrogen production daily, and an adult woman produces an average of 480,000 nanograms of estrogen daily. The point is, not that these relatively higher levels of estrogen in eggs or humans are harmful (this is not the case), but that the level of estrogen in implanted beef is minuscule.

A second or reimplant is often considered, especially in “longer day” cattle-those fed more than 100 to 150 days. Many variables have to be considered when deciding whether or not to reimplant, and there is no single answer.

Consideration must be given to the type of cattle being fed (sex, breed, weight, condition on arrival, genetic potential, etc). In addition, the layout and facilities of the feedyard may or may not be conducive to reworking the cattle for reimplanting.

Many reimplanted cattle weigh in excess of 800 pounds and the working facilities should be adequate to safely and effectively handle these larger cattle. Excessive stress or injuries could defeat the economic gain of the reimplant.

If reimplanting is performed, consider this trip through the chute an opportunity to perform other health-related procedures. These might include a respiratory virus revaccination to abate late day respiratory pulls; a seven-way clostridial revaccination for enterotoxemia and blackleg; or a pour-on or dip for lice.

Proper technique is vital to the efficacy and performance of the implant. An experienced, conscientious person “at the head” when processing cattle will make the feedyard money. Special attention to sanitation and proper placement is imperative.

Currently, available implants are required to be placed subcutaneous on the dorsal surface of the ear outside the annular cartilage ring. After implantation, the implant should be easily palpable and away from any potential trim sites. Avoid any blood vessels or previous implants and ear-tag first so as not to disrupt an implant site.

We encourage processing crews to use sharp implant needles, change them when dull, and lay the needle on a disinfectant-soaked sponge between usages. Do not dip the needle in a liquid disinfectant as this moistens the inner core, causing partial dissolution and “gumming” of implants.

It is helpful to run occasional checks to evaluate implant technique. This may be done either at initial processing, when doctoring cattle, at reimplantation, or on a post mortem check at an abattoir. Crushing or bunching implants may result in over-absorption and decreased duration of efficacy. Abscessed implants, walled-off implants, and implants placed in the cartilage of the ear may result in under-absorption and decreased efficacy.

The buller syndrome sometimes is tied to implants. Though there may be some relationship, this problem probably is more related to technique, rather than brand of implant used. In our experience, the buller syndrome is a multi-factorial problem—more tied to season of the year, weather patterns, type, age and breed of cattle, bunk management and pen space per head.

Growth Promotants

Classification		Ingredients
Product

Category I
Active Days = < 70
Low Estrogen Equivalent
Ralgro		36 mg Zeranol
Synovex C		10 mg Estradiol Benzoate, 100 mg Progesterone
Component E-C		10 mg Estradiol Benzoate, 100 mg Progesterone
Revalor G		8 mg Estradiol, 40 mg TBA
Synovex T40		8mg Estradiol, 40 mg TBA
Component TEG		8 mg Estradiol, 40 mg TBA

Category II
Active Days = >70, <90
Strong Estrogen Equivalent
Synovex S		20 mg Estradiol Benzoate, 200 mg Progesterone
Synovex H		20 mg Estradiol Benzoate, 200 mg Testosterone Propionate
Component E-S		20 mg Estradiol Benzoate, 200 mg Progesterone
Component E-H		20 mg Estradiol Benzoate, 200 mg Testosterone Propionate
Ralgro Magnum		72 mg Zernol
Compudose		25.7 mg Estradiol 17-B
Encore		43.9 mg Estradiol 17-B

Category III
Active Days = > 90, < 110
Low TBA Equivalent
Revalor S		24 mg Estradiol, 120 mg TBA
Synovex T120		24 mg Estradiol, 120 mg TBA

What is Pre-conditioning?

2004-07-01T13:58:00.000-07:00

The Bovine Respiratory Disease Complex (BRDC) results from a complex series of steps: (1.) stress, (2.) viral infection, and (3.) bacterial infection.

Stress can be caused by routine procedures such as castration, dehorning, nutrition, weather (change of environment), congregation (co-mingling) and transportation. Stress causes the entire body to be more prone to infection. This occurs by allowing disease causing organisms easier route of entry and by disarming some of the body’s important defense mechanisms against disease.

Viruses that commonly take advantage of the situation usually include IBR and BVD. Other viruses such as BRSV and PI3 sometimes can cause problems. Although viruses may cause death, the major role they play in the BRDC is to allow the third factor-bacteria-to gain a foothold and possibly lead to death.

Mannhemia haemolytica, Pasteurella multocida, and Haemophilus somnus account for

the majority of bacterial infections of the BRDC.

This complex series of steps causing the BRDC with large economic losses with high morbidity and mortality resulted in the development of pre-conditioning.

Pre-conditioning programs vary considerably, but generally include weaning, training to eat and drink from troughs, vaccination, and treatment for internal and external parasites, castration, and dehorning. Pre-conditioning is a general term used in the beef industry to basically describe the time period and management of calves which takes place at the farm/ranch before arrival into the feedyard. Therefore, pre-conditioning can be defined as the preparation of feeder calves for the marketing and shipment to the feedyard. Pre-conditioning is intended to give the calf time to return to normal behaviors, improve feed intake, and allow time for the immune system to rebound from weaning stress and immunization. (Bartle, Steve ADM Alliance Nutrition) Don’t confuse or compare the term pre-conditioning towards backgrounding. Backgrounding is a similar approach; however, the vaccinations and other management procedures take place at a separate facility-not at the farm/ranch.

American Association of Bovine Practitioners (AABP 1968) defined the following areas in pre-conditioning:

Weaned at least three weeks before sale.
Trained to eat from a feed bunk and to drink from a trough
Treated for parasites.
Vaccinated for blackleg, malignant edema, PI3, IBR, Pasteurella, and sometimes BVD and Haemophilus.
Castrated and dehorned.
Identified with an ear tag.
Sold through special auctions

Historically, most pre-conditioning programs supported a 21-30 day weaning period; however, more recent efforts have been directed toward increasing the number of days weaned before shipment and improving management procedures on the ranch. The Texas Ranch to Rail data shows it take at least 45 days for calves to develop independent behaviors, achieve consistent intake targets, and to develop immunity from vaccination. Therefore today, most programs require a 45-day weaning period. Several pre-conditioning programs have also been replaced by individual programs developed at the producer level and by commercial programs promoted by biological firms. (Radostits, Otto Third Edition)

The vaccination requirements also vary but most include modified live vaccines such as IBR, BVD, PI3, BRSV, Mannheimia haemolytica leukotoxoid, and clostridial bacterins. In any pre-conditioning program, it’s important to meet beef quality assurance standards and all label directions should be followed regarding injection location, dosage, needle size, and timing of vaccination including boosters.

Different alliances of which this author works with have different requirements but a general outline includes:

Ownership-cows or calves originate from pre-conditioned facility
Bulls must be castrated and healed before shipment
Calves dehorned or tipped and healed before shipment
Calves must be weaned for 45 days or longer
Treated for internal and external parasite
Vaccination program:
At branding or six weeks prior to weaning:
A vaccine containing chemically altered modified-live IBR and PI3, modified- live BRSV and inactivated BVD.
Seven-way clostridial bacterin
Mannheimia haemolytica leukotoxoid or Mannheimia haemolytica and Pasteruella multocidia combination
Radio frequency identification ear tag
At weaning:
Revaccinate with modified-live IBR, PI3, BRSV and BVD
Heifers will need to be palpated and determined open or an abortion program must be implemented at point of origin.

The nutrition and management during the pre-conditioning period is dependent upon the producer’s objective. Oklahoma State University (extension publication F-3031) list several possible objectives:

· Optimize condition and health for the pre-condition phase

· Produce added weight at low cost

· Market calves through a program requiring pre-conditioning for best market potential

· Minimize the risk of digestive upsets and disease

· Achieve a specific target weight.

Suggested Nutrient Recommendations for Stressed Calves

(Adapted from 1996 Nutrient Requirements for Beef Cattle)
Dry Matter,%------------------- 80-85
Concentrate,%------------------ 50-75

NEm, Mcal/lb------------------- 0.82-0.90

NEg, Mcal/lb-------------------- 0.46-0.56

Crude Protein,%----------------- 12.5-14.5

Calcium,%----------------------- 0.60-0.80

Phosphorus,%------------------- 0.40-0.50

Potassiun,%---------------------- 0.80-1.40

Magnesium,%-------------------- 0.20-0.30

Sodium,%------------------------- 0.20-0.30

Copper,ppm------------------------- 10-15

Iron,ppm----------------------------- 100-200

Manganese,ppm-------------------- 20-40

Zinc,ppm---------------------------- 75-100

Cobalt,ppm-------------------------- 0.10-0.20

Selnium,ppm------------------------ 0.10-0.20

Iodine,ppm-------------------------- 0.30-0.60

Vitamin A, IU/lb------------------- 2500

Vitamin E, IU/lb------------------- 50-100

Management practices that minimize weaning and arrival stress will result in fewer calves requiring health treatments. The importance about prevention of disease, particularly the BRDC, does not only affects the morbidity (health treatments) and mortality (deathloss) but data also shows the impact on average daily gain, feed efficiency and carcass merit.

Health and Performance Effects of Preweaning Management

(Reprinted from Cattle Health Tech)

How does preweaning management influence disease resistance, average daily gain, feed efficiency, quality grade, and yield grade of carcasses? This question has been addressed in various research projects over the course of several years.

1. Compared to fresh, unweaned calves, calves that were preweaned and fed for 30-45 days at the ranch had:

20 % less sickness and death loss
Similar average daily gain
2%-to 7% poorer feed conversion

2. Compared to fresh, unweaned calves, calves that were limit creep fed (1-3 lb/head/day) for the last 60 days had:

20 % less sickness
25 % less death loss
0%-3% better feed conversion

3. Compared to polled steers, calves that must be castrated and/or dehorned/tipped at the feedyard generally had:

3 % poorer average daily gain
3 % poorer feed conversion
Lower quality grade at slaughter (castration only)

4. Compared to nonvaccinated calves, calves that were vaccinated for IBR, BVD, PI3, BRSV and Pasteurella on the ranch had:

20 % to 30 % less sickness
40 % less death loss
Similar feedyard performance.

The Texas A & M Ranch to Rail program has consistently shown an impact of health on the ability of steers to express their genetic potential and the costs associated with sick cattle beyond the cost of medicine. Healthy steers had an average of $93.20 more favorable return than sick steers in the 20003 program and an average net return over a five-year period has been $37.54 per head.

General Rules for Treatment in the Feedyard

2004-07-01T13:57:00.000-07:00

In the feedyard, questions arise daily concerning medication programs for respiratory disease. It’s the single biggest disease problem.

When faced with a history of no response to medication, we spend very little time on the actual medications. The more important consideration is determining management procedures aimed at prevention and treatment of diseased cattle.

Following are some rules of treatment that need to be observed when evaluating a

feedyard health program. They also are good guidelines when training new personnel to pull and treat sick cattle.

Pull Sick Animals Early

The first and foremost rule of treatment is to pull sick animals early, pull appropriately and treat aggressively.

If sick animals are not pulled from the pen before respiratory disease becomes an advanced problem, medication response will generally be very poor.

Good pen riders are able to spot animals just as they are breaking with pneumonia. This corresponds to the latter stages of the incubation period of disease and is before the animal actually shows clinical signs. It takes a certain eye to be a good pen rider; some

cowboys seem to have it instinctively; others have developed it over the years.

Pull Animals Properly

Animals must be pulled for sickness appropriately. If sick animals are not pulled properly, they will not get the hospital care they need, hospital pens will become needlessly overcrowded, and the doctor crew will become overworked.

Heavy pulls do not always coincide with proper pulls. Sometimes, heavy pulls from a pen occur, leaving some sick animals and pulling some with no obvious signs of illness. If heavy pulls occur in a pen (greater than 25%), then steps should be taken toward

mass medication.

Treat Aggressively

What does treating aggressively mean? It means that when an animal is pulled initially for respiratory disease, it is treated with strong therapeutic agents (antibiotics) that will stop pneumonia at its earliest stages, and not allow further progression of the disease

process. This will effectively decrease total treatment days, decrease the number of retreatments and, of course, prevent high death losses.

With good therapeutic agents and supportive care, sick animals will not have to be rested between treatments, if additional treatment is deemed necessary. Antibiotics are stressful on the animal’s system, so supportive measures are used to stabilize the adverse changes that occur following treatment, as well as treat the disease.

Supportive Care

Supportive care includes such drugs as (1) B-complex vitamins, to stimulate the appetite and replenish body loss, (2) antihistamines to open swollen, narrowed airways, and

(3) electrolytes to replace body water loss as well as body electrolyte loss.

The primary objective of supportive care is to counteract the serious side effects of disease and subsequent changes referable to antibiotic usage. Supportive care also includes nutritional support in the form of fresh hay and high-energy rations, plus hospital

management aimed at prevention of overcrowding and further stress.

All drugs used in beef cattle, including antibiotics and supportive medications, have a specific purpose and use. Your consulting veterinarian is the best source of information on proper use of these drugs. The feedyard health crew must be well versed on the

proper use of drugs because a drug used improperly is sometimes worse than no medication at all.

Visual Inspection

Visual inspection of sick animals in the hospital is absolutely necessary. Occasionally feedyard personnel will look at the thermometer and forget to look at the animal.

To prevent this oversight, all animals should be given a severity code, such as severely sick, moderately sick or mildly sick. This simple system encourages the health crew to assign a uniform code to the sickness of all animals.

This coding system allows sequential assessment of sick pulls and progress through the hospital treatment program. Secondary benefits of this system allow various persons to treat the animal on subsequent days and assess response to treatment. Also, it allows assessment of sick animal pulling.

Three-Day Treatment

If you are using an antibiotic that requires daily administration, treatment of sick animals should be continued for at least three successive days. This can be accomplished with one shot or administration or with three successive days of treatment. In the end, this will decrease the treatments and the pen deaths following treatment.

Research and experience has shown that only one or two days of treatment has detrimental side effects. Antibiotics can be changed during these three-day periods, but not after only one day of treatment.

Alternate routes of administration or increased dosages can be used on the second day of treatment when added response is needed on this treatment day. If treatment response is inadequate after two days of therapy, then alternate treatments or increased dosages should be considered.

You never want to give up on the treatment of an animal, but you should realize the limitations of antibiotic therapy and strike a happy median between cost-benefit and continued treatment. It is very discouraging to treat an animal day after day, only to have it die after an extended treatment period.

As a general rule, treatment of a sick animal for six continuous days or three treatments will constitute adequate treatment. Continued treatment often will result in a chronically sick animal or a dead animal.

Accurate Records

The last rule of treatment is the keeping of clear, concise and accurate records. The feedyard runs on paperwork. Because of the large numbers of cattle that any feedyard handles and many sick animals that are treated, records are absolutely essential. These records will not only provide bookkeeping services, but will allow you to assess treatment response. Records must be (a) easy to fill out, (b) supply the appropriate information, and (c) be easily compiled for further evaluation.

These rules are formulated from sound medical practice and experience. Some of them vary depending on your particular antibiotic or medication program. But they will, in most cases, result in a successful medication program.

Mass Medication – The Practice and Problems

2003-09-26T13:55:00.000-07:00

Mass medication programs are useful when used appropriately in food animal production. But your goal should be kept in focus when deciding the method, route of administration and product to be used.

The treatment may be preventive or therapeutic, or a combination of the two, depending upon the stage of the disease in question in the individuals comprising the group treated. When utilized effectively, mass medication is a medically and economically sound procedure, combining veterinary science with practical production economics. On the other hand, when misused or misdirected, it can be an inefficient additional expense and a confounding factor to satisfactory therapy. Mass medication is defined as “the administration of a pharmaceutical product to an entire group of food animals for disease control purposes.” This treatment usually includes antibiotics directed at bacteria, mycoplasmas or rickettsia and compounds controlling

coccidial infections.

Goals of Mass Medication

Two main goals—morbidity and mortality control—are most often the focus of mass medication programs in food animals. Morbidity control is more easily and effectively achieved; mortality control is more difficult.

Morbidity

Morbidity is defined as the cumulative sum or percentage of animals that must be removed from their pen or herdmates for individual treatment. Costs incurred on these animals include not only direct medical costs, but also the time and money spent in removing and holding them in a separate location for treatment and returning them back to the group.

By controlling morbidity, at least one of the following three objectives are realized:

1. Health costs are minimized when treating the entire group with mass medication (plus the remaining sick individuals after mass treatment), resulting in less total dollars spent than treating all sick animals on an individual basis from the start.

2. Facilities are inadequate to handle a large number of sick animals on an individual basis, thus making mass treatment more cost effective than facility construction or expansion.

3. Personnel are lacking in time or capability to handle a large number of sick animals on an individual basis, thus making mass treatment more cost effective than hiring more or better capable personnel.

On a strictly medical cost return example, let’s assume that the mass medication of a group of 100 animals undergoing a disease outbreak costs $2 per head for a total of $200. And assume that the cost to treat an individual animal for the disease is $15. Using these figures, mass medication in order to be cost effective, would have to prevent or stop the disease in at least 14 animals that otherwise would have required individual treatment. Remember, this solely assesses the return on a medical cost basis and does not include facility or personnel costs, or additional losses occurring when an animal must be separated from the group.

Mortality

Mortality, defined as the sum or percentage of dead cattle out of the subject group, is more difficult to alter directly with mass medication. Certainly when indirect factors such as inadequate facilities or poor ability to identify sick individuals early are a consideration, then mass medication may improve the final mortality rate.

However, when all aspects of individual cattle identification and treatment are adequate and uncompromised, mass medication as a rule does not decrease overall mortality. Some sick individuals require more therapeutic care and supportive management than what can be provided in a mass medication program. Additionally, mass treatment can make sick animals harder to identify by temporarily abating the clinical signs but allowing a relapse back into clinical disease one to several days after the program.

Any medical procedure, including mass medication, can be evaluated by four criteria:

1. Cost. Is the expense of the mass treatment justified as compared to the results expected or observed with less expensive products or combinations?

2. Stress. How stressful is the mass treatment on the cattle? Does clinical benefit compensate for the stress involved?

3. Efficacy. How effective is the mass treatment (in vitro and in vivo)?

4. Convenience. How easy is the mass treatment and does the convenience compensate for any shortcomings?

Route Of Administration

Several types and forms of products are available utilizing various routes of administration. The route chosen depends upon the disease being treated, the facilities and husbandry conditions and the economics of the delivery system or procedure. Here are four alternative routes:

1. Feed. Several feed ingredients are available and approved for mass medication in beef cattle. The key factor in successful group medication is consumption of adequate levels of the ingredient by all or most of the group. As simple as this sounds, it often is overlooked. Either uneven mixing practices, behavioral eating patterns or individual animal anorexia due to disease may influence the outcome of mass medication.

Sick animals often go off feed. So mass medication should be geared as a preventive approach early if respiratory disease control is the focus.

Oxytetracycline and chlortetracycline are available as feed additives for disease control. Additionally, oxytetracycline is available in combination with neomycin, and chlortetracycline is available in combination with sulfamethazine. Indications for use and withdrawal times vary with the level or dose of the product included.

Besides being included into mixed feed in a microingredient or premix form, these products are also available in a crumbles or pellet form to be top dressed over feed. The crumbles and pellets have shown to be especially palatable to cattle and may stimulate increased consumption as a secondary benefit.

For control of coccidiosis, four feed ingredients have been approved: amprolium, decoquinate, lasalocid and monensin. In determining which product to use, it’s important to know (a) the life cycle of the coccidial organism, (b) the duration of time it must be fed, and (c) how to include it in a feeding program. Also, each product differs in approvals to be fed with other ingredients and this must be considered.

Tylosin is also approved as a feed ingredient with a primary role of liver abscess control in feeder cattle.

2. Water. Fewer products are available to medicate water than for feed. Sulfonamides are the antibacterial compounds available for medicating water. The same principle applies to water medications as with feed—the animals must drink the water in order to receive a benefit. Water medications can decrease the palatability of the water, and this may increase the uncertainty of adequate delivery of the medication to appropriate animals. In an attempt to overcome this, flavored gelatin powder has been added with the medication to alter the smell and taste of the water. Practitioners vary in their preference of flavor to be added. To achieve the effective dose required, the mechanics of water medication must be monitored closely to ensure that the proper amount is added initially and maintained through the medicating period. Continuous flow or automatic refill tank systems prove unmanageable, so all sources of water must be manually filled and medicated.

3. Oral. Individual oral medications require that the animal be caught and restrained for administration of the product. Liquid and bolus forms are available. The liquids include neomycin sulfate and some sulfonamides. These are primarily for bacterial enteritis and absorption through the GI tract is limited. The liquid medications are administered through a drench wand or hook.

The boluses available consist of one or a combination of sulfonamides and neomycin sulfate. They are approved for the treatment of enteritis, respiratory disease and foot rot. Absorption across the GI tract must occur at significant levels in order to reach target tissues of lung and feet.

Long-acting, sustained release boluses containing a sulfonamide are available, giving 48 to 72 hours of therapeutic blood levels from a single administration. Boluses are time-consuming to administer and adequate head restraint must be obtained. Multi-dose balling guns are frequently used to administer boluses but have been shown to result in a higher incidence of pharyngeal trauma and abscessation than single dose equipment. This may be a consideration during mass medication of a large group when time becomes a factor.

4. Injectable. Antimicrobials alone or in combination represent a high percentage of all the mass medication regimens performed on food animals. However, increasing concerns over injection site trauma and scarring in muscle tissue has led to the reevaluation of many habitually routine procedures, not the least of which is intramuscular mass medication.

The intramuscular, subcutaneous and intravenous routes of administration have all been used for mass medication purposes. The intramuscular route has been the method of choice until recent concerns about carcass quality. The neck area is the site for both intramuscular and subcutaneous injections. A disadvantage of intramuscular injection of mass medications is the muscle soreness that can develop with some products or combinations. The propylene glycol-based products and 200 mg/ml products are especially noted for this. In extreme cases, the stress caused by muscle soreness precludes any therapeutic benefit achieved from the injection.

The subcutaneous route of injection becomes increasingly more popular when compatible with the medication being administered. Though some scarring may occur, the muscle trims at carcass fabrication are minor compared to intramuscular injections. Large volumes of medication are more easily accommodated. Technique is critical to obtain a true subcutaneous injection, and it is preferable to manually “tent” the skin prior to needle insertion to avoid abrasion of underlying muscle tissues.

The intravenous route of administration is desirable for compatible products due to negligible impact on carcass quality. But like the oral boluses, this often proves too time-consuming and inconvenient for mass medication purposes. If injectable sulfonamides are used, however, this route must be utilized as it is the only approved route of administration for these products.

Long-acting injectable antimicrobial formulations are currently available. Long-acting oxytetracycline is available in a 200 mg/ml and 300 mg/ml preparation. Long-acting

combinations of procaine penicillin G and benzathine penicillin are also being marketed commercially. Another parenteral administration is the use of Tilmicosin at the label dose of 10 mg/kg.

Previously, bioavailability and convenience were the major concerns regarding mass medication routes of administration. However, recent pressures from the beef packing industry, and subsequent response and investigation by production-oriented veterinarians and producer organizations, have prompted new research and focus on injection site dynamics and tissue characteristics.

Mass medication techniques are especially suspect when a majority, or all, of the food animals in a particular group are medicated. It is critical that all animals medicated are somehow identified so appropriate withdrawal times may be observed and potential carcass trims at slaughter may be traced back to the problem procedure.

Specific Program Applications

In the feedyard. Mass medication programs are widely utilized in receiving programs on high risk stressed or sick cattle. Injectable antibiotics or combinations are the most common form of treatment.

Respiratory disease is the main focus and these programs are geared toward morbidity control. Intramuscular and subcutaneous routes of administration are the norm and programs vary from one to three days in duration.

Occasionally during prolonged wet or dry periods, foot rot reaches epidemic proportions in a feedyard. Individual therapy is effective; however, many of these cattle are in the finishing phase of the feeding period. So it is costly (in lost performance) to remove them from their home pen and inconvenient to a follow a withdrawal period.

Mass medication with a feedgrade tetracycline has proven effective in stopping epidemic foot rot. Oxytetracycline fed at just less than two grams per head per day has no withdrawal requirement and is an effective prophylaxis against further cases; also, it’s therapeutic in mild to moderate cases already present.

Tylosin is available in feed additive form for control of liver abscesses. Prior to the introduction of this practice, it was common to feed one of the tetracyclines at high levels (2-4 grams) three days a month for the same purpose.

Decoquinate, lasalocid, or monensin are commonly fed as a coccidiostat in receiving and starting rations. Factors affecting the choice as to which is fed include (a) the degree of challenge, (b) concomitant approvals with other additives and (c) feeding program.

Amprolium also has been approved and used as a treatment for clinical coccidiosis, as well as being apreventive compound.

In stocker operations. Mass medication in stocker cattle is widely utilized, much as in high risk stressed or sick feeder cattle. But many stocker operations don’t have holding and working facilities to handle sick cattle. Thus, individual animals must be roped and thrown or driven long distances to facilities in order to be treated. Either scenario is highly stressful and may not be conductive to a satisfactory treatment response.

Therefore, it often is cost effective to aggressively mass medicate received cattle in order to minimize, if not prevent morbidity. Parenteral aminoglycosides, particularly neomycin, require extremely long and somewhat unpredictable withdrawal periods—200 days or more in some cases—and should not be used to avoid a violative residue.

Surfactants, though not antimicrobials, are commonly placed in the water of stocker cattle for bloat prevention. This is especially useful in high moisture, rapidly growing legume pastures where bloat potential is high. Of course, enough surfactant must be ingested, within tolerable palatability limits, to prevent a frothy bloat in the rumen. When they quit drinking, you have added too much.

In cow-calf operations. Antimicrobial mass medication in cow-calf herds usually is directed at calf disease. Antibiotics may be included in creep feed as prophylaxis against respiratory disease, although this is generally unsuccessful since sick calves usually back off the creep feed. Individual calves are often caught and handled one time during an outbreak and given long-lasting oxytetracycline injection and longacting sulfa boluses.

Weaned calves also can be medicated through the water with sulfonamides. This proves too costly in sucking calves, however, because they share a common water source with the cow and most of the medication goes to the cow.

Anaplasmosis control in cows has been achieved with mass medication in endemic or problem areas. For prophylactic purposes, constant feeding of a tetracycline at low to moderate levels has been utilized. During an acute outbreak, herds can be medicated with intramuscular long-lasting oxytetracycline at 9 mg/lb body weight.

For prevention of grass tetany and milk fever, magnesium and calcium can be provided to cows on a mass medication basis. This is usually in the form of free choice mineral licks or blocks.

Additionally, prostaglandins have been injected on a mass basis for estrus synchronization in cow herds.

Mass Medication Criteria

Since the decision to mass medicate a group of animals is quite subjective, here are several criteria to consider:

1. Clinical appearance and past performance of similar cattle. This requires a key person to evaluate the animals upon arrival and daily thereafter in determining the need for mass medication. A knowledge of the morbidity/mortality patterns of previous animals from the same origin is helpful. A keen ability to observe and clinically evaluate the group also is helpful.

2. Morbidity patterns. This criterion proves useful for deciding when to mass medicate for respiratory disease in the feedlot. When morbidity exceeds predetermined percentages, either on a daily or cumulative basis, mass medication is indicated. For example, a pull rate out of a pen of 10% any one day or a cumulative 25% over a three-to-five day period indicates mass medication.

3. Feed consumption. When routinely measured, feed consumption can serve as an early indicator of an impending disease break, before observable clinical signs appear. A sudden drop in feed consumption suggests mass medication should be considered, particularly in high risk cattle.

4. Body temperature. When cattle are being worked as a group, rectal temperature has been used as a judgment criterion to selectively medicate individuals. Individuals below the selected temperature point receive either no antibiotic or a less expensive, less efficacious one.

However, it must be recognized that (a) temperature elevations occur for reasons other than infection and (b) animals harboring a bacterial infection do not always maintain a fever.

The ambient environmental temperature, the animal’s disposition, and the order in which the animal is worked in the group can all elevate the body temperature. Conversely, extended disease progressing to a weak moribund animal or previous treatment with corticosteroids can lower the body temperature.

Choosing the Product

Product choices are reasonably clear cut for the feed, water and oral routes of mass medication. The injectable route is not so clear.

Here are some characteristics to consider when selecting an injectable mass medication program:

1. FDA approved for use in beef cattle. Extralabel drug usage currently is left to the discretion of the veterinarian under some general guidelines. Abuse of this privilege may jeopardize the veterinarian’s position.

2. Inexpensive. Return on the money spent is the key here. Will an expensive but highly efficacious drug afford results that justify its use over a less expensive and possibly less efficacious drug?

3. Effective against respiratory and GI pathogens. These conditions are common and frequently found simultaneously in the same animal.

4. Active in small volumes. Injection mechanics and tissue damage are more likely and of more concern with large volume formulations.

5. Non-irritating upon injection. Injection site scarring and the stress of muscle soreness must be weighed against clinical benefit.

6. Wide safety margin. Accurate dosing may prove difficult in a group with variable weights. Narrow safety margins increase the chance of overdosing and causing adverse reactions or toxicity.

7. Easy to administer. The intramuscular and subcutaneous routes remain the easiest methods of delivery.

8. No interference with subsequent antibiotic use. There are many theories and questions exist as to resistant bacterial strains after antibiotic administration. Most likely, resistance develops against antibiotics after previous treatment with a different one.

9. Does not mask effects of disease condition. The alteration of an infection from clinical to subclinical adversely affects sick animal identification. Also, early or continued treatment can facilitate the development of a chronic disease.

10. Short withdrawal time. Extended withdrawal times preclude the option to recognize and pull poorly performing animals. Also, it increases the risk of violative residues and, in extreme cases, may delay the marketing of a finished animal.

When choosing a specific injectable product or combination for mass medication, bacterial cultures and sensitivity determinations are of value, if time permits.

Some antibiotics show 100% efficacy continuously over time, i.e. ceftiofur, sulfachlorpyridazine, and trimethoprim/sulfa on isolates of Pasteurella-Mannheimia/Hemophilas. Unfortunately, however, 100% cure rates are rarely experienced because effective antibiotic therapy is just one aspect of achieving a cure. The best results come from ongoing culture and sensitivity monitoring.

In summary, mass medication is a health management tool that, when used appropriately, results in cost savings and sound economic return to the food animal producer. Careful planning and consideration should precede the implementation of a mass treatment program, clearly defining the goal to be achieved and a detailed plan of execution. For economic as well as professional reasons, indiscriminate administration of antibiotics to large groups of

food animals should be avoided.

The Interstitial Pneumonias

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The term interstitial pneumonia or alveolar epithelial hyperplasia has been used to designate the lung diseases in which there are inflammatory lesions of the septa or dividing wall of the air sacs or alveolar of the lung.

The term and understanding of “atypical” pneumonia has been difficult, particularly in regard to terminology and etiology. All of these terms have been used interchangeably:

1.Acute Bovine Pulmonary Emphysema (ABPE) “Fog Fever”

2.Atypical Interstitial Pneumonia (AIP) Usually seen in the feedyard environment.

3.Pulmonary Adenomatosis “Farmer’s Lung”

4.Acute Respiratory Distress Syndrome (ARDS) Plant toxins, etc

Acute Bovine Pulmonary Emphysema (ABPE),”Fog Fever”, is an acute respiratory distress syndrome that usually occurs in the fall in adult beef cattle moved from dry, sparse overgrazed pasture to lush, green pasture. Almost all

outbreaks of ABPE occur within two weeks of pasture change. ABPE is caused by ruminal production of 3- methylindale (3MI) from ingested

L-tryptophan (TRP) in the feedstuffs.

Adult breed cows are most commonly affected because this is the type of animal most likely to be subjected to abrupt pasture change.The type of pasture appears to be unimportant, as long it is lush.

In severe cases there is an acute onset of severe dyspnea (difficult breathing) with a loud expiratory grunt, frothing at the mouth and open mouth breathing with tachypnea (rapid breathing). It is important to note that coughing is not

prominent.

In animals that die, ecchymotic to petechial hemorrhages occur in the larynx, trachea and bronchi with frothy fluid is present in the airways, and there will be congestion and edema of the lung giving it a smooth, glistening, and

glasslike appearance.

An Acute Respiratory Distress Syndrome (ARDS) is any respiratory condition characterized clinically by a sudden onset of severe dyspnea (difficult breathing) and pulmonary lesions of congestion, edema, thickening of the alveolar epithelium and interstitial emphysema. One example of ARDS would be Moldy Sweet Potato toxicity, which is caused by ingestion of a furanoterpenoid toxin.

There is an acute onset of tachypnea and hyperpnea (rapid excessive breathing), tachycardia, and dyspnea with loud expiratory grunting, frothing at the mouth, extension of the head and neck, flaring of the nostrils and frequent deep coughing. Signs usually occur within 1 day of exposure and death may occur 2-5 days.

At necropsy the lungs are wet, firm, enlarged and fail to collapse with yellow gelantinous edema fluid and emphysema throughout.

Pulmonary adenomatosis, “Farmer’s Lung”, is an allergic respiratory disease caused by inhalation of organic dusts. Farmer’s Lung is caused by exposure

to the dust from moldy hay, grain, or other vegetable matter containing spores and products of themophilic actinomycetes such as Micropolyspora

faeni and Thermoactinomyces vulgaris.

Pulmonary adenomatosis is a disease of confined adult cattle, primarily dairy cattle. Typically a succession of acute cases occurs during the winter housing period. The acute form is indicative of recent exposure and is characterized by a sudden onset of dullness, decreased appetite, hypogalactia, coughing, expiratory tachypnea, and dyspnea. There is a moderate transit fever. The chronic form is insidious in onset and may not be detected until there is considerable fibrosis. Some may not be detected until turned out in the spring

when increased exercise causes an acute crisis. There is a history of weight loss and coughing for several winters with remission in the grazing season.

If the condition can be arrested before significant fibrosis occurs, the prognosis is good.

Farmer’s Lung is a problem in areas with wet summers and severe winters, a situation that results in the combination of moldy hay and housing of cattle in the winter. Bailing and stacking of hay with a high moisture content results in overheating of the stacks. Thermophilic molds are released when the hay is distributed for feeding.

At necropsy, in acute cases, the lungs are superficially grossly normal; however, with closer examination small gray spots in many lobules

will be noticed.

The primary interstitial pneumonia of feedlot cattle is Atypical Interstitial Pneumonia (AIP) which is also accompanied with edema and emphysema of the lung.

Affected animals have an acute onset of severe breathing difficulty and majority die regardless of treatment. Lungs from animals that have died from AIP are enlarged, rubbery and have a mottled (checkerboard) interstitial emphysema appearance. In the Bovine Respiratory Disease Complex (BRDC) the pathology involvement of the lung is usually fibrinous and found in the lower ventral portion of the lung whereas in AIP the upper or dorsal part of the

lung is involved.

The exact cause is not known. Some studies suggest that it may be related to dietary factors, and dust since it is most often seen in the summer months and also may be associated with lung disease such as Bovine Respiratory Syncytial Virus (BRSV).

The diseases discussed are all characterized by diffuse pulmonary involvement and by marked alveolar epithelial hyperplasia. The disease called AIP includes those cases that are pathologically similar to ABPE and ARDS but epidemiologically different. Future research can be expected to reveal additional etiologic agents.

A survey is presently being conducted in cooperation with University of Georgia and Colorado State University and with feedlots and veterinary consultants regarding the management factors and other diseases that may lead to the

development of AIP. The aim of this survey is to gather information regarding size, geographic location, and management factors from feedlots where AIP is a problem and also from feedlots where the disease is not a problem. The information will help point researchers in the right direction in future research to determine the cause of Atypical Interstitial Pneumonia.

References:

Breeze, Roger, Carlson, James R.; Current VeterinarymTherapy I – Food Animal Practice, pp 832-725

Hjerpe, C.A.; The Lungs and Mediastinum. Bovine Medicine and Surgery – Second Edition, pp 714-725

Smith, J.A., “The Interstial Pneumonia,” Large Animal Medicine, 1990 Bradford P.Smith, pp 596-608

BRD Complex Viral Conditions, ETC

2003-05-01T13:53:00.000-07:00

BVD Infection of Feedyard Cattle

If you ever want to start an argument in a feedyard about vaccination programs, mention BVD (bovine virus diarrhea). The folklore, myths and half-truths concerning this virus are many. BVD does play a key role in feedlot respiratory disease, but we are unsure

of its exact role and even more unsure of possible control methods.

BVD was first described in 1946 as a severe and often fatal disease of dairy cattle. Early researchers named this disorder “mucosal disease” and many people still call the severe digestive form of BVD by this name. We now know that BVD can affect other organs, including the respiratory and immune systems. Because of the complexity of this disease, we do not completely understand all the effects of BVD virus on cattle.

BVD in the feedyard can mimic many other diseases or show no obvious signs at all. Common clinical signs include depression, off-feed, discharge from the eyes and nose, coughing and rapid respiration. These signs may or may not progress to a severe

watery diarrhea with ulcers in the mouth and entire digestive system. This set of signs could account for any of a number of diseases seen in feedlot cattle and explains why it is important to avoid a diagnosis of BVD from clinical signs alone.

In order to put this viral disease in perspective, let’s look at the effects of BVD on the respiratory system and the Bovine Respiratory Disease complex.

BVD has two prime effects on the respiratory system. First is a direct negative effect on the local disease fighting mechanisms of the lungs and upper respiratory tract. Second, BVD virus can cause a severe disruption in the body’s immune system.

The end result is that the BVD infected animal is more susceptible to any infection, but most importantly bacterial pneumonia such as Pasteurella haemolytica(Mannheimia haemolytica), Pasteurella multocida and Hemophilus somnus. Mycoplasma bovis may also play a role.

In order to have a problem with BVD in a feedyard, you must have two factors present: (1) a susceptible animal and (2) a virus capable of causing disease.

Of course, salebarn cattle and freshly weaned calves are more susceptible to any disease challenge. Also, some strains of virus are capable of causing disease to greater extent than other strains.

If you take a highly susceptible calf that has been freshly weaned and expose it to an extremely hot virus in the feedyard, the outcome usually is death. Conversely, if

the cattle are protected against BVD or non-stressed, the same virus may have little to no effect on them.

Control of BVD

There are three schools of thought concerning BVD vaccination:

1. First, all cattle must be vaccinated with a modified live virus (MLV). This procedure has one serious drawback. Any MLV vaccination on stressed calves is potentially harmful, but the effects of MLV BVD vaccines can be even more harmful than most by causing immunosuppression of an already compromised animal. There are good MLV BVD vaccines that confer adequate protection to feedlot cattle with minimal side effects, but the potential for this adverse reaction is present with many MLV BVD vaccines.

2. The second school of thought says vaccinate for BVD with a killed product. Killed products have been much improved over the last few years and offer good protection without causing adverse reactions. Opponents of these vaccines agree that protection is adequate, but rather slow in appearing.

3. The third school of thought is that BVD vaccination has no effect on respiratory disease in a feedlot.

In our practice, recommendations on BVD vaccination are based upon the type of cattle fed, past health history and confirmed presence of BVD problems through diagnostic techniques.

In summary, BVD has the potential to cause serious problems in feedlot cattle. The key to control lies in proper diagnosis and sound preventative measures.

Respiratory Syncytial Virus Vaccine

Currently, two modified live vaccines and one killed respiratory syncytial virus vaccines are available for use in beef cattle. In order to understand the potential use of these products, let us examine this virus, its clinical manifestations and application of vaccination to a feedlot health program.

Bovine Respiratory Syncytial Virus (BRSV) is named because of its ability to form syncytia in infected cells. Syncytia are simply an aggregation of cells that clump together in a large mass with an indistinct internal structure.

This virus was first seen in Europe and Japan. Reports of outbreaks in the U.S. were first seen in Nebraska and Colorado. A human counterpart has been recognized that has many similarities to the virus seen in cattle.

When BRSV is exposed to susceptible cattle, an incubation period of 2 to 10 days can be expected.

Clinical signs during an outbreak are of rapid onset and include increased respiratory rate, depression and discharges from the eyes and nose. Salivation or slobbering is common and may be blood-tinged as can the discharge seen coming from the nose. Coughing is usually marked and seems to persist throughout the course of infection. Swelling may occur around the eyes but is usually pronounced in the throat region. Body temperatures are increased and range from 104° to 108° F. Abortions usually are not seen but some have been reported.

The disease outbreak can affect all ages of cattle, but is usually most pronounced in freshly weaned calves. Infections can range from mild to marked and affects a large number of cattle, but usually with a low death loss. As with any virus infection, bacterial pneumonia can be a secondary invader.

The clinical picture of BRSV can resemble other viral infections such as IBR, PI3 or BVD, except that the disease is usually mild and the marked swelling in the throat latch is rather unique.

Other viral infections such as those mentioned can cause much higher death losses; but early in the outbreak there has been confusion as to the actual agent involved. Many times BRSV has not been identified until other common viral agents have been eliminated

as the causative agent.

As yet, in our feedyard experiences, the problems with BRSV have been minimal. That is, we have not recognized this condition in the pure form. This is not to say that BRSV has not been involved in certain respiratory problems. As with other viral agents, over-

growth of Mannheimia haemolytica or Pasteurella multocida may actually mask the true initiator of the problem. BRSV can cause severe damage to the trachea

and lung, which would then allow for bacterial pneumonia to occur.

In order to diagnose BRSV as a problem, you must attempt to isolate the virus from the lung, trachea or nasal secretions. The affected lung must also be examined under the microscope for the syncytial formation so characteristic of this disease. These two procedures may prove very unfruitful in the feedlot environment.

Blood samples and serology taken at the time of respiratory outbreak and repeated 2 to 4 weeks postoutbreak are the most beneficial method of positive diagnosis currently. Continued development of more accurate and effective diagnostic techniques is under way.

In summary, Bovine Respiratory Syncytial Virus is usually a mild viral infection which can be relatively severe under some circumstances. This disease is usually a problem in freshly weaned calves, but can be a problem in any age of cattle.

Other Respiratory Diseases

Many times when we talk about respiratory disease, infectious bronchopneumonia or Bovine Respiratory Disease Complex (BRDC) is the focal point.

In the feedyard, other forms of respiratory disorders exist. Diphtheria and “hardbreathers” or “honkers” can be problems, although not as common as BRDC.

Diphtheria

Diphtheria is an infectious disorder of the upper airways. A focal point of damage usually occurs to the larynx or voice box and allows for opportunistic invasion of the damaged airway lining by bacteria. The bacteria that invades the airway is the same organism that causes foot rot in cattle.

Symptoms of the calf affected with diphtheria may include difficulty in breathing, excessive salivation, swelling around the throatlatch and increased body temperature. Often the most obvious clinical sign is the foul smelling breath that occurs. Because of the bacterial invasion of airway tissues and the particular pathogenic organisms involved, dead tissue is

formed at the site of infection causing the fetid odor.

Diphtheria in a feedyard may often be an uncommon occurrence, but may occur secondary to feeding coarse feedstuffs, in the form of hay or finished feed. Other outbreaks of widespread diphtheria have not been attributed to any known factors.

Treatment for the condition is generally quite satisfactory, if treated symptomatically with a broad spectrum antibiotic. Treatment should also include therapeutic agents to decrease swelling and increase the overall airway opening. Swelling in the voice box or larynx

area can lead to a greatly decreased airway capacity.

Hardbreathers

Hardbreathers or honkers are frequently seen in the feedyard. A hardbreather is an animal that usually has 45 to 60 days or more on feed. It generally is seen in a pen of cattle having difficulty breathing. Depending on the severity, a “honk” may be heard as air is expelled.

Hardbreathers are not caused by a single condition, but by several possible conditions. These conditions may include (1) IBR, (2) acute spread of a low level pneumonia,

(3) allergic tracheitis, (4) atypical interstitial pneumonia, or (5) respiratory syncytial virus.

It is difficult, if not impossible, to tell which of these conditions the animal has when it is pulled. Laboratory tests and response to treatment are necessary to separate these five causes of a hardbreather. And it is important to know the causes before proper

treatment can be instituted.

Acute IBR

Acute IBR infection is seen as a single condition in cattle with greater than 45 to 60 days on feed. Cattle often have severe respiratory difficulty and a high body temperature (in excess of 105°F). A blood tinged nasal discharge may also be present.

Animals with low grade pneumonia which previous therapy failed to completely resolve the condition, often are triggered by the IBR virus into an active, more severe respiratory condition.

As the animal becomes closer to finish and fatter, the digestive tract is pushed forward into the diaphragm causing pressure on the previously compromised lung thus causing less total function air space and many times death.

Allergic Tracheitis

Allergic tracheitis and atypical interstitial pneumonia are actually an acute response to chronic exposure to allergy – causing moldy feed or other airborne allergenic particles. These animals appear very suddenly with no previous indication that there was a problem.

Such cases may occur when the animals are moved longer distances, as might occur to reimplant. Airway space was adequate when in the pen, but the exertion of movement caused the animal to become decompensated and thus suffer an acute lack of necessary

oxygen.

Respiratory Syncytial Virus

Respiratory Syncytial Virus (RSV) has been reported by some to be a cause of allergic tracheitis and atypical interstitial pneumonia. It is unclear at this time as to the significance of this condition in fat cattle pneumonia.

Therapeutic goals for these conditions are relatively simple: (1) avoid any procedure at the time of treatment that would increase the animal’s need for additional oxygen; (2) supply therapy to open narrowed airways; (3) reduce swelling and possible allergic reaction; and

(4) treat with a short withdrawal antibiotic.

Animals treated may respond favorably at first only to relapse soon after treatment is completed. Therefore, you should keep the option of early slaughter open should treatment response be unsuccessful.

Even though the incidence of fat cattle respiratory conditions is much less than BRDC in newly arrived cattle, the economic losses incurred are much greater per animal affected. For example, an animal lost soon after arrival will realize an economic loss that is roughly two-thirds that of an animal that is near finish. Therefore, it is easy to see that keeping the animal

healthy throughout the feeding period is important for efficient economic returns.

More information may be received through Beef Production Medicine which can be purchased in the publication section of this web site.

Respiratory Disease of Feeder Cattle

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Respiratory disease of cattle is known by various names – pasteurella pneumonia, shipping fever or Bovine Respiratory Disease complex.

No matter what it is called, this disease accounts for huge economic losses every year. So it is important for cattlemen to be familiar with recognition, treatment and prevention of this disease.

There are several types of respiratory disease, but the one of most concern is the infectious form. We all are familiar with the calf that has pneumonia. This sick calf will be depressed, drawn, gaunt and unwilling to move. It will cough, breathe rapidly, have a yellowish

discharge from the eyes and nose, and have a fever of 103° to 106° F.

The first thing we often do when we see these signs is reach for a bottle of antibiotic. Rather than reach for a bottle of antibiotic, let’s look at the factors that interact to cause pneumonia. Once we better understand these factors, we can work toward more effective prevention and treatment programs.

Pneumonia results from a complex series of steps that are only partly understood. Research has shown that three factors must be present for a calf to get sick with pneumonia: (1) stress, (2) viral infection and (3) bacterial infection. Stress can be caused by routine

procedures such as castrating and dehorning. Also, new situations – nutrition, weather, congregation and transportation – can induce stress.

When a calf is stressed, its body reacts by secreting hormones that positively and negatively affect bodily functions. On the negative side, stress causes the entire body to be more prone to infection. This occurs by allowing disease causing organisms easier routes of entry and by disarming some of the body’s important defense mechanisms against disease.

So the first step toward pneumonia occurs following a stressful event.

The second step takes place when the body’s defenses are down and viruses invade the nose and other parts of the respiratory system. Viruses that commonly take advantage of this situation usually include IBR and BVD. Other viruses such as BRSV and PI3 sometimes cause problems.

Virus infection in cattle could be compared to the common cold or flu in humans, which rarely cause death. Although viruses may cause death, the major role they play in pneumonia is to allow the third factor of this disease – bacteria – to gain a foothold and possibly lead to death.

Pasteurella haemolytica (Mannheimia haemolytica) and Pasteurella multocida and Hemophilus somnus account for the majority of bacterial infections of pneumonia.

These bacteria gain entry via infected nasal secretions (much like virus particles may), or they may be stimulated to grow from normally low populations in the throat. Either way, without proper recognition and antibiotic treatment, these organisms can cause death

rather quickly in affected animals.

Since antibiotics kill or inhibit growth of bacteria, these are the organisms that we are trying to eliminate when we use drugs such as an antibiotic.

Respiratory Viral Disease

Respiratory viral disease can be devastating to animal health. It continues to be poorly understood and treated with mediocre results.

Viruses are not actually alive but are particles of genetic material that must infect the animal’s own living cells before they can reproduce and cause damage. The use of antibiotics will not directly fight a viral infection; but in most instances, antibiotics are indicated to treat the coinciding bacterial disease.

Viruses are spread from one animal to another via (a) direct nose-to-nose contact,
(b) contact with nasal secretions or other bodily exudates from an infected animal, or

in a feedyard, so we must concentrate our efforts on prevention and control-mainly with timely vaccination- preferably before exposure to the disease causing virus.

The four most common respiratory viruses are IBR, PI3, BVD and BRSV.

IBR (infectious bovine rhinotracheitis) has also been called “rednose.” It causes a reddened, tender nasal surface that crusts over and peels, as well as sore and runny eyes. Internally, the animal’s trachea or windpipe becomes very inflamed and may fill up with

a thick exudate. IBR has also been implicated in genital infections in cows, as well as in central nervoussystem disorders.

PI3 (parainfluenza 3) has long been recognized as a respiratory pathogen in cattle, especially lightweight calves. Its most harmful characteristics is that it destroys the cilia (hairlike projections) in the trachea, which prevent foreign matter and bacteria from

entering the lungs.

BVD (bovine virus diarrhea) has long been recognized to cause problems in the digestive tract, but in recent years has been implicated as a respiratory agent. BVD is very immunosuppressive; it weakens the animal’s immune system and thereby lessens its

ability to fight disease. Some cattle have been proven to be chronic carriers of one type of BVD and develop severe digestive and respiratory disease when exposed to another strain. Unfortunately, there is no practical and quick way to identify these animals, and we have

no accurate estimate of the extent of this problem.

An Ounce of Prevention: Feedyard Receiving Programs

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Computerization has helped us evaluate the costs of disease and the savings through prevention. As a result, our focuses in feedyard health programs have evolved away from antibiotic treatment and mass medication. The new focus is towards vaccination, stress management and immune competence. The objective is to block or minimize the processes that amplify disease susceptibility.

Feedyard veterinarians face a unique challenge. No other food animal production is as variable and non-integrated as the beef industry. Repeated transportation, resulting in environmental and nutritional changes, is the norm rather than the exception. Thus,

the types and degrees of stress must be identified and addressed. A strategic receiving program should be designed and executed with the same organization and detail as a processing or treatment program.

The Three “Rs”

Many of the needs of stressed cattle are summed by the three R’s of a receiving program: rest, rehydration, and rumen. Transported cattle become physically fatigued from standing especially if hauled long distances over 12 to 24 hours. Additionally, mental stress can be a factor due to loading, unloading and commingling with unfamiliar cattle.

We recommend that a spacious, dry (or bedded) pen be provided during receiving. Specific parameters include 150 to 200 square feet of pen space per head and 12 to 16 inches of feedbunk space per head. If bedding is used, be sure it is removed when it becomes wet or soiled. If left in place, it becomes a seedbed for contamination and infection.

Before stressed cattle are processed, a rest of at least 12 to 24 hours is suggested. Research test after test shows how stress compromises current immune function, as well as further development of immunity. A rest period simply allows the animal to regain some of the immunocompetence that transportation and marketing stressors have disfavored.

So rested cattle respond better to the vaccines administered during processing. Practical observations have suggested that a 1/2% to 1% increase in morbidity is seen for each 24 hour delay in processing after arrival. Of course, short-haul, healthy country cattle experience minimal stress and immediate processing can be performed as a matter of convenience. Also, highly stressed sick cattle may need immediate handling if they merit mass or individual treatment. If this is the case, recognize that prevention has given way to treatment and results rarely are optimal. Keen observers learn through practice and experience how to differentiate between sick cattle and stressed cattle. The veterinarian may check white blood cells counts, plus serum glucose levels and fibrinogen, to

aid in this differentiation.

Rehydration of transported or water-deprived cattle is crucial. Weight loss or shrink during transport or other handling procedures consists of “fill” loss and tissue losses. Fill consists of digestive tract contents and bladder contents at initial weigh-up. Tissue losses are made up of evaporative, urinary and even fecal losses at some point when fill is gone. Tissue losses result in some degree of dehydration as well as disruption of extracellular and intracellular

fluid components. Experience and recent research show that in shrinks greater than 7%, stress is significant. And in long-haul cattle it can be significant when shrink is less than 4%.

Unreasonably low shrinks may indicate a high degree of previous loss before initial weigh-up. Rehydration is more critical initially than feed consumption. The old industry practice of holding cattle off water to make them consume feed is unsound. Free choice, clean, fresh water should be available at all times. We avoid water medication whenever possible, as

it may alter palatability and water intake. (One exception has been a commercial vitamin E additive that actually seemed attractive to cattle.) Do not assume that cattle are drinking just because water is available. Electric current, unpalatable or toxic contents, ice and

ignorance of location may deter or prevent water intake. Water troughs in receiving pens should be checked and cleaned daily.

The final R (for rumen) is representative of a large array of nutritional needs. Highly available energy is critical to restore energy balance in the food-deprived animal. But beware of over-consumption, which can lead to metabolic and/or clinical acidosis. The energy-depleted animal may be in a catabolic state, breaking down muscle and other proteins for

energy sources. Protein supplementation provides readily available amino acids to aid in slowing and reversing the catabolic process. Non-protein nitrogen should be avoided, however, due to both palatability and toxicity problems. Recently, much attention has been given to vitamins and trace minerals, especially in relation to immune development and protection of tissues. Particular focus has been on vitamins A, C and E, plus the micro-elements zinc, copper and selenium. Research results show this to be promising. Remember, however, it is critical that a physiological balance be maintained on these compounds and

elements. Over-supplementation is at best inefficient, and it can be toxic.

Roughage, the Natural Foodstuff

Roughage provides early fill in the deprived rumen and acts as a substrate for microflora. Reestablishment begins with forage (hay), the natural foodstuff of the ruminant. Native long-stem high quality grass hay is preferable. It can attract cattle to a bunk, and it can deter them from walking fencelines. Starter ration recommendations vary greatly, though a general consensus suggests the following: Energy is provided in a medium level concentrate

(about 55%). This is based on a 500 pound calf; and for every 100-pound decrease in body weight, a 10% increase in concentrate is recommended. High levels of protein (13% to 14%) should be provided from a natural protein source. Vitamins and trace minerals should be assessed for need based upon other ration components and cattle source and condition.

Health and performance are very dependent on the job done in the receiving period. Before any thought is given to processing and treatment programs, a detailed and effective receiving program should be implemented.

Biosecurity-An Extension of Herd Health Management and Emergency Preparedness

2002-01-07T13:49:00.000-08:00

Biosecurity-An Extension of Herd Health Management and Emergency Preparedness
Terrorism is defined as an act of terrorizing or state of being terrorized by intimidation.
Those weapons available to terrorists for intimidation include chemicals, biological, radiological, nuclear and explosive.
Biological terrorism involves the use of microorganisms or toxins derived from living organisms to induce death or disease in human beings, animals or plants.
A microorganism to be pathogenic and effective in biological terrorism against animal agriculture must be highly infectious and contagious, have the ability to survive in the environment, have predictable clinical disease pattern (including morbidity and mortality), be pathogenic to livestock and poultry, easy to acquire or produce, attributable to as if it was caused by a natural outbreak, not harmful to person causing the infection and easily spread. Foot and Mouth Disease (FMD) is one example that meets these criteria and also poses the greatest potential threat to the cattle industry.
Biosecurity is defined as a comprehensive management program to avoid introduction of virulent (FMD) and zoonotic (a disease of animals that can be transmitted to humans-Anthrax) disease causing pathogens into a livestock herd, non-confinement and confinement, and to prevent the movement of these pathogens within the herd.
Biosecurity, as an international, worldwide practice of protecting animals from infectious diseases, has become a major concern with the worldwide threat of Foot and Mouth disease (FMD) and Bovine Spongiform Encephalopathy (BSE).
A high percentage of beef operations are managed with an open herd policy that allows entry or re-entry of animals or animal products. During calving season, foster calves may be grafted onto cows. Feedyards and stocker operations commingle cattle routinely. Seedstock operations use artificial insemination or embryo transplants throughout the breeding season. All these management practices, which have been discussed in the management section of this book, place beef operations, cow-calf, stocker, and feedlot operations at risk of disease.
To plan an effective Biosecurity Herd Health Management Program (BHHMP), a risk analysis should be conducted.
     1. Risk assessment
         Identify the level of any infectious diseases already existing, identify and prioritize     those diseases targeted for control and identify the diseases not present and you wish to continue to exclude. i.e.-Bovine Respiratory Disease Complex and Foot & Mouth Disease
     2. Risk management
         Formulate a comprehensive prevention health program and implement.
     3. Risk communication
         Explain the plan to management, personnel, suppliers and customers to ensure buy-in and implementation.
     4. Collate and analysis results frequently.
The first step is to know the complete condition of your operation- herd health, nutrition and facilities. Be aware of potential diseases, how they are contacted and the risks.
Biosecurity can be broken down into external and internal components.
     External Biosecurity: The rules and procedures implemented to avoid contamination of the herd from outside sources.
     Internal Biosecurity: The rules and procedures implemented to avoid any spread of disease within the herd.
Many of the components of a Biosecurity Herd Health Management Program are just good common sense.
Biosecurity Herd Health Management Programs (BHHMP) programs should include all management, prevention and treatment procedures. See Chart #1.
     External and Internal    1. An awareness of diseases-both domestic and foreign. See Chart #2
    2. Disease management-prevention, incubation, treatment and risks.
    3. An accurate evaluation of health and nutrition of herd.
    4. Strict herd health and vaccination programs
    5. Health, vaccination and production records of purchased animals
     Internal     1. Where possible quarantine program and separate facilities for new animals
     2. Isolation, hospital pen for sick animals
     3. Clean, sanitary cattle equipment, facilities and lots
     External     1. Ability to control human traffic-control access to property, provide disposable protective clothing and provide disinfectant for incoming visitors.
     2. Ability to control herd contacts/purchases.
     3. Regular veterinary inspection and consultation.
Biological security measures are becoming standard in many agricultural sectors. The USDA has implemented three levels for its personnel to follow to minimize the risk of disease introduction. For more detailed information go to www.aphis.usda.gov/oa/fmdbiose.html.
Biosecurity Levels
Routine levels of biosecurity measures are described below. When in doubt
as to which level of biosecurity is needed, choose the higher level. These
steps should be repeated for each premises that is visited.
Level 1- Visits to farms or ranches that entail office or home visits only.
        No contact with livestock or their housing (including pet horse or work dog).
        Use the minimum measures such as:
        Minimum Biosecurity Measures
        1. Avoid livestock areas, pens, barns, etc., unless it is necessary to complete the goal of the visit.
        2. Park your vehicle on paved or concrete areas, away from production sites on farm, to avoid contact with dirt, mud or manure. If not possible, be certain that tires are free of dirt and debris by hosing the tires and wheel wells before leaving the premises. If this does not clean the tires adequately, take the vehicle to a nearby pressure car wash.
        3. Wash hands with soap and water or an antibacterial gel before entering and after leaving the premises to avoid transmitting disease agents from person to person.
Level 2- Visits to farms or ranches where minimal contact with livestock or
their housing (barns, pens, hutches, etc) is unavoidable to attain the goal of the visit,
i.e. property appraisals, tour of production facilities.
Contact constitutes walking through animal housing or pastures where the animals are not within reach.
        1. Apply minimum biosecurity measures plus:
        2. Immediately put on clean rubber or new plastic boots upon exiting the vehicle.
        3. After returning to your vehicle, clean and disinfect any equipment used with a brush and approved EPA disinfectant solution (see listed supplies- Chart 3).
        4. Clean rubber boots with an approved EPA disinfectant diluted with water.
           Scrub the bottoms of the boots with a brush to remove all dirt or debris.
        5. Dispose of disinfectant solution according to the label. Unused
      disinfectant solution should not be discarded on ground.
        6. If wearing plastic boots, place them in a plastic bag that should be left on the premises for the owner/producer for disposal or place in a designated dirty' area of your vehicle.

Level 3- Visits to farms/ranches where there will be close contact
livestock. This includes contact such as walking through narrowly confined pens/ lots where animals are within reach or actually handling/inspecting the animals.
        1. Apply measures used in Levels 1 & 2 plus:
        2. Pre-plan the needed supplies and clothing for daily visits.
        3. Use a pair of clean coveralls for each premises.
        4. Designate a 'dirty' area in your vehicle for clothing and equipment that
       has been used on the farm.
        5. Put on clean coveralls and rubber boots immediately upon exiting the
       vehicle.
        6. After returning to your vehicle, clean and disinfect all equipment used
       (including eyewear) and place all disposable supplies in a plastic bag to
        leave with the owner/producer for disposal. If not possible, place plastic
       bag in the 'dirty' area of the vehicle and dispose of in a manner that
       prevents exposure to other livestock.
        7. Clean rubber boots with an approved EPA disinfectant diluted with water.
        8. Scrub the bottoms of the boots with a brush to remove all dirt or debris.
        9. Dispose of disinfectant solution according to the label. Unused disinfectant
       solution should not be discarded on ground.
        10. Remove coveralls so that they are inside out and place in a garbage bag.
        11. Place the clean equipment and boots in the designated 'clean' area of the
       vehicle.
        12. If the vehicle was not parked on a paved surface, wash vehicle tires and
       wheel wells to remove dirt and debris at a nearby pressure car wash.
        13. At the end of the day, dispose of all plastic bags that contain dirty supplies in a manner that prevents exposure to other livestock. Launder all coveralls.
        14. Personal hygiene should include shampooing hair and cleaning under fingernails.
Gempler’s, Inc describes a biosecurity program as an insurance policy for the health and productivity of the herd. It will not be free. Producers must make decisions about their "risk tolerance level" based on the chances of a disease occurring and the expected economic losses from the disease.
There must be planning, commitment and education of all personnel throughout the operation to attain the goals set for an effective Biosecurity Herd Health Management Program (BHHMP).

The components of a biosecurity program are all good management practices that will optimize beef production, increase the profitability and ensure a safe food supply.
The ultimate fate of our industry is on the line, and collective anti-terrorism actions must be a top objective for all in the industry.
Resources for biosecurity information can be assessed at:
http://www.biosecuritycenter.org/. Purdue University. This site offers a list of peer-reviewed biosecurity references, disinfectant information, and state regulations involving dead animal disposal, reportable diseases and nutrient management.
www.gemplers.com/biosecurity.htm Gempler’s Inc
http://www.humanitarian.net/biodefense Humanitarian Resource Instiute
http://www.beef.org/ National Cattleman’s Beef Association
http://www.drovers.com/ The Drovers
http://www.usda.gov/ Department of Agriculture
www.aphis.usda.gov/vs/ Veterinary Services
www.avma.org/vmat/default.asp American Veterinary Medical Association
http://www.firstgov.gov/ For government information

Preshipment Programs for Beef Cattle

2001-12-01T13:49:00.000-08:00

Preshipment Programs for Beef Cattle
Tradition and economics form the basis for current methods of marketing beef cattle. The present marketing system has somewhat divided the industry, resulting in limited communication between the calf-producing segment and the feedyards. However, several attempts have been made to change the system with various alliance programs.
The system of marketing cattle impacts the veterinarian’s work, because of increased diseases that occur when cattle are congregated, stressed and transported to feedyards.
The greatest health problem—bovine respiratory disease complex—is estimated to cost the beef industry $250 million to $750 million annually. Cow-calf producers, order buyers, salebarn owners, back-grounders and feedyard operators strive to maximize production and minimize expenses and disease loss. Now they are giving a renewed attention to the maximization of animal health through procedures performed before the animal reaches the feedyard.
Various programs have been used for several years that are specifically intended to prepare an animal for shipment. Some are designed for a particular feedyard or grazing operation. Programs also have been formulated that allow cattle to progress through the marketing system with a minimum of health-related disorders at the gathering point before shipment to the feedyard. Collectively, these programs are referred to as preshipment programs.
Preshipment preparation is thus defined as those procedures performed before or during shipment that better prepare the animal for subsequent grazing or feeding at a particular operation.
Preshipment programs are similar to preconditioning programs in that both are designed to increase cost-effectiveness during the first few weeks at the final destination.
Preconditioning programs (before a calf leaves its original home) have been slow in coming, because ranchers feel they don’t get paid for the additional trouble and cost. The costs of preconditioning involve labor, feed health products and veterinary services.
Preshipment programs use only procedures that give direct cost benefits to the buyer. Eliminated are the questionably cost effective procedures of extended feeding, parasite control, giving commercial implants and surgery. The cost of these programs is fully borne by the buyer of the cattle.
The goal of preshipment programs is not to fully process cattle at the point of origin but rather to meet immediate medical, immunologic and nutritional needs in order to (1) better enable these animals to face the stresses of transport and commingling, and (2) minimize the physiologic disruption that occurs at this time.
Programs are divided into (a) those for use at the ranch (before exposure to respiratory pathogens) and (b) those for use at the order buyer’s facility or salebarn.
The programs outlined here are intended to be examples. As with other animal health programs, input and guidance from the veterinarian is essential in forming a program that meets the needs of the cattle involved.

Ranch Program
In Texas Panhandle feedyards, numerous calves are received from large ranches; especially some located in New Mexico and Arizona. Most of the cattle are received during the fall, are freshly weaned and are native-type British or British crossbreeds.
These calves come from isolated environments with little or no exposure to the common respiratory pathogens they will face in the feedyard. Rarely do they have previous vaccination and they appear to be immunologically naive on arrival at the feedyard.
Initially, these calves experience acceptable health and performance (less than 0.5% mortality) until approximately days 21 to 28 on feed. At this time, a sharp decrease in feed consumption is observed, followed by a dramatic increase in cattle requiring treatment for respiratory disease. In five to seven days, morbidity peaks (25 to 35 days on feed) at approximately 25%; while overall morbidity for the feeding period can approach 50%. Mortality rates for cattle involved in the outbreak average 2% to 4%.
Diagnostic information gained from these out-breaks and from subsequent study of the herd environment demonstrated that calves become sick and die because of mixed viral and bacterial bronchopneumonia. Bovine viral diarrhea (BVD), Pasteurella haemolytica (Mannheimia) and Hemophilus somnus often are cultured in the laboratory.
Increased susceptibility apparently stems from the lack of exposure at the ranch and the immunologic naive of calves on arrival at the salebarn or the feedyard. Feedlot practitioners have found that low level of selenium or copper increase health problems. However, there is no data to support these claims. The problem present in these calves also occurs in other calves that originate in the western United States and in Florida. Preshipment programs involving calf vaccination have helped.
The calves are inoculated at least 21 days before shipment to the feedyard. Studies show that calves vaccinated then do have an adequate period in which to develop primary immunity by the time they are shipped to the feedyard. Weight loss incurred in handling the cattle at this time normally is not a problem for the seller. Inoculation is aimed at controlling viral and bacterial agents known to be associated with bovine respiratory disease complex.
If the calves are still nursing at this time and there is concern about the use of a modified live virus and shedding by pregnant cows, alternatives are a temperature-sensitive intranasal IBR-PI3 or a killed virus product.
The nutritional status of calves should be addressed if history shows that it is difficult to start them on feed. Creep feeding can be implemented approximately 21 days before shipment. Thus, the calves become accustomed to a concentrate ration and to eating from a bunk.
Studies have demonstrated that limited creep feeding is cost-effective at the ranch, improves later feedlot performance, and provides health advantages. But, weaning before shipment has had variable effects on weight gain at the ranch. Therefore, preweaning is not specifically recommended in this program.
Order Buyer Program
Historically, the order buyer has functioned as the intermediary between the cattle seller and the feedyard or stocker operator. Order buyers draw from large geographic areas in order to supply a buyer with a specified type of cattle, a process that can takes normally five to seven days; however, it may take as long as two or three weeks. During this time, health problems can be encountered that are not fully realized until receipt at the buyer’s locale.
Inadequate nutrition and management can predispose to respiratory and digestive disorders. Cattle purchased from salebarns can have pre-existing health problems and serve as sources of infection for other susceptible animals.
Cattle held or sorted at the order buyer’s facility can become sick as they are subjected to the stresses of commingling, crowding and a contaminated environment. Most order buyers do their best to supply healthy, high-quality cattle, but they are faced with a difficult task because of the volume of cattle they handle and the cost of preventive and therapeutic procedures.
Many order buyers are willing to cooperate on a preshipment program prescribed by the feedyard veterinarian. Identifying problems seen on and shortly after arrival at the feedyard is the key to program design. The preshipment program at the level of the order buyer should focus on (a) proper nutrition, (b) correcting bacterial infectious processes, and (c) stimulating effective active immunity for respiratory pathogens.
On arrival or when gathered at the order buyer’s facility, the cattle are vaccinated with an intranasal modified live IBR-PI3. This establishes a relatively rapid onset of upper-airway secretory immunoglobulin A immunity and stimulates the release of interferon. Interferon provides some cross-protection against other viruses, such as adenovirus and rhinovirus. Respiratory and digestive diseases can be combated by giving antibiotic therapy just before shipment.
The question often arises: Should antibiotics be included in the feed to deal with disease problems? Because feed consumption is highly variable among individual animals, especially those that are sick, injectable antibiotics would be more therapeutic and cost-effective.
Although attention to nutrition at the order buyer’s facility may be inconvenient, it is cost-effective and benefits health and performance. A 55% concentrate diet, plus free-choice native grass hay is the optimum preshipment diet for stressed cattle. However, when grain exceeds 55% of the total ration, there is an increase in morbidity.
Cattle fed this type of preshipment diet have health and performance advantages that extend to the first few weeks at the feedyard.
Salebarn Program
Many stocker cattle and feeder cattle are bought at auction markets. The risk of infection from exposure to pathogenic organisms is limited if cattle spend minimal time in the market environment.
If the cattle are traded by a middleman or hauled from sale to sale with the idea of making a modest immediate profit, health problems will be intensified. Disease—primarily respiratory and digestive disease—will occur as a result of poor nutrition, repeated stresses of transport, water and food deprivation, and commingling.
Because cattle normally are not kept at salebarns for extended periods, a one-time preshipment program focusing on treatment of existing disease and establishment of quick upper-airway immunity has been beneficial.
Market veterinarians are knowledgeable about the antibiotic sensitivity pattern of a particular salebarn and can be helpful in implementing a program.
Nutritional support can be difficult at salebarns, because of the high turnover rate of cattle as well as the lack of direct cattle ownership by the salebarn operator. At least, cattle should have fresh, clean water and hay available in the holding pens. Ideally, a 55% concentrate ration also would be available, but labor and expense usually make this cost-prohibitive.
Failure to provide adequate nutritional support can cause die off of normal ruminal microflora and can result in decreased fermentative and digestive capacity of the rumen. Probiotics have become popular in treating ruminal malfunction; they are quick and easy to give.
The easier and more economical that preshipment procedures are to perform, the more likely you will get cooperation in carrying out these procedures at the point of origin. Ongoing communication with the people who execute the program is necessary to ensure results.
Generally, the impetus for initiating a preshipment program starts with the buyer. The veterinarian involved in the salebarn or with the order buyer also can initiate cost-effective programs that will benefit the client and the health of the cattle care.

New & Old Antibiotic Selection Concerns

2001-10-01T13:47:00.000-07:00

Introduction:

The cattle feeding industry is a highly specialized, efficient means of beef production; however, because the industry transports cattle over great distances, congregates them in confined areas, and exposes them to a concentrated energy ration, we see a complicated bovine respiratory disease syndrome. Despite the knowledge of the veterinarian, know-how and skill of pen riders and hospital crews, bovine respiratory disease complex (BRDC) remains the cattle- feeding industry’s number-one disease challenge.

1.) Preventative Medicine
a.) Pre-Arrival
b.) Arrival
2.) Nutrition
3.) Environmental Management
4.) Personnel Management
5.) Hospital Management
a.) Therapeutic Management
b.) Records Management

The objective of the receiving program is to ensure that incoming cattle acclimate to the finishing period as efficiently and atraumatically as possible. The typical feedlot handles cattle from extremely divergent backgrounds with widely varied nutritional experience and immunologic status. A small management error in this starting/receiving period can be greatly magnified.
The management of BRDC is not as simple as we would like or expect it to be. Clinical evaluation upon on arrival will alert feedlot personnel to potential problems. Subjective data should include origin, weight, type of cattle, length of transport, season of the year and ambient weather conditions. Objective data would include per-cent shrink, classical respiratory signs and number of visibly sick animals.
Cattle are routinely classified into risk categories:
1.) High Risk-exposed
No history of vaccination, sale barn/auction market origin and usually considered "put-togethers" com-mingled.
Morbidity normally occurs first week following arrival.
2.) High Risk-unexposed
No history of vaccination; however, usually one source origin.
Morbidity usually occurs after typical 7-10 day incubation period and normally sees an 18-21 day break. These can be difficult and require a re-vaccination.
3.) Low Risk
History of vaccination for BRDC and weaned for minimum of 30 days.
Low risk vaccination program which is usually only a booster.
The processing of cattle includes those procedures and medications deemed necessary to maximize performance and minimize health-related losses. The actual act of processing most commonly occurs upon arrival; however, in order to circumvent some of the shortcomings processing after exposure to disease causing factors; alternative approaches need to be examined.
Clostridia diseases, internal and external parasites, and BRDC account for a majority of the monetary losses due to high morbidity, high medication, poor performance or death.

Choosing an appropriate treatment program and its success depends equally upon the management of both healthy and sick cattle and the choice of medicines.
Antibiotics are used both from a treatment and preventative standpoint in processing programs. Antibiotics can be utilized effectively in the preventative area but four common mistakes can be encountered. First, timing of antibiotic administration may be too early (bacterial infection not occurring) or too late (extreme damage already present to internal organs) to effect a response. Secondly, the amount of antibiotics given is not enough to ensure significant bacterial control. Thirdly, improper administration of an effective product may also result in inadequate response. Lastly, combinations or "cocktails" of antibiotics can render the ingredients inactive and cause other quality assurance residue concerns.
The goal for each animal entering the hospital for treatment should be a lasting cure (minimum repull per cent). Achieving that means accurate and specific identification of the disease; proper evaluation and treatment; and re-evaluation prior to leaving the sick pen.
When data from feedyards is summarized, 7.2 percent of cattle received treatments for various reasons of which 83 percent during seasonal peaks of this total morbidity is attributed to BRDC.The key to successfully manage BRDC is the feedlot’s management health team, headed by the veterinarian, ability to formulate a comprehensive health program, which consists of:
Majority of pen the riders are capable to spot animals just as they are breaking with pneumonia. Animals’ exhibiting signs such as:
The first and foremost rule of a hospital and therapeutic program is to pull early, pull appropriately, and treat aggressively (easier said than done). If sick animals are not pulled from the pen before respiratory disease has become an advanced problem; medication response will generally be very poor. This corresponds to the latter stages of the incubation period of disease and is before the animal actually shows classical clinical signs of disease.
-Depression/lethargy,
-Loss of appetite,
-Stiff gait/soreness when walking,
-Crusty muzzle,
-Salivation,
-Mild diarrhea,
-Rapid, shallow breathing,
-Moist cough,
or a combination of these signs or symptoms should be pulled for evaluation and treatment. Acutely affected animals respond best to treatment, and animals treated earlier in the course of the disease have a better chance of recovering
-Eye and/or nasal discharge,. Animals must be pulled for sickness appropriately. If sick animals are not managed properly then these animals will not get the hospital care they need, hospital pens will become overcrowded, and the hospital crew will needlessly become overwhelmed. Heavy pulls don’t always coincide with proper pulls.
To treat aggressively in the feedyard means that when an animal is pulled initially for BRDC he is treated with an antibiotic program based on input from the feedyard’s veterinarian that will stop pnemoumia at its earliest stage of development, and not allow further progression of the disease process. These will effectively decreases total treatment days, decrease the number of retreatments, and prevent high death losses.
Antibiotic selection can be done by antemortem testing, postmortem testing, clinical response evaluation, and with properly designed field studies. Clinical response rate evaluation is best tool for treatment of BRDC.

If using an antibiotic that requires daily administration, treatment of sick animals should be continued for at least three successive days. Depending upon the antibiotic, this can be accomplished with one injection or administration or with three successive days of treatment. This rule is important in order to decrease total number of treatment days, number of treatments, and the number of pen deaths after treatment.

Treatment should include antibiotics as well as other medications that are supportive in nature. Supportive care includes such drugs as B-complex vitamins to stimulate an appetite and replenish body loss, antihistamines to open swollen, narrowed airways, and electrolytes to replace body fluid loss as well as electrolyte loss.
All drugs used in beef cattle have a specific purpose and use. It is important that the feedyard health crew be well versed on the proper use of drugs used in the treatment of sick animals. A drug used improperly is sometimes worse than no medication at all.

Hospital treatment records are essential for calculating:
First Therapy Response
Relapse Rate
Case Fatality Rate
Chronic Rate
5.) Weight Gain/Loss
According to the University of Nebraska’s Great Plains Veterinary Education Center, sick calves gaining more than 5 percent of their body weight while in the hospital pen had a repull rate of only 3 percent; whereas, those losing weight had a repull rate of 34 percent.

Cost of Treatment
When evaluating records and treatment response risk classification, age of animals, morbidity patterns and season of the year must be considered.
Achieving a lasting cure involves teamwork from everyone on the feedlot’s health team. From a pen rider’s ability to identify sick calves, to a hospital crew’s evaluation and treatment decisions, with the knowledge and skill of the feedlot’s veterinarian and capability to communicate with the feedlot personnel will have a tremendous impact on the bottom line. The more informed and capable its members, the better equipped they’ll be to make accurate, profitable care decisions and the more likely sick animals will achieve a lasting cure.
The last rule of treatment is keeping of clear and accurate records. These records should not only provide bookkeeping services but also allow to adequately assessing treatment response.

Infectious Diseases

2001-06-11T13:41:00.000-07:00

Infectious Diseases that Threaten the United States Beef Industry

Infectious Disease is defined as any disease caused by the entrance, growth and multiplication of bacteria, protozoon’s or viruses in the body. An infectious disease may or may not be contagious.

Contagious Disease is defined as a type of infectious disease caused by receiving living germs directly from an affected animal with the disease or by contact with a secretion or some object previously contaminated.

Many infectious diseases are not contagious, but some special method of spreading or inoculation of the germs is required.

Foot-and-Mouth Disease (FMD) is one of the most dreaded infectious diseases in the world and difficult to control. It is caused by a highly contagious aphthovirus of the family Picornaviridae and has no cure. It infects cattle but also pigs, sheep, goats, buffalo and artiodactyl wildlife species- animals with cloven hooves. FMD is characterized by fever, vesicles in the mouth and on the muzzle, teats, and feet; eventhough the mortality is low, it can cause death in young animals.

There are seven immunologically distinct types: A, O, C, Asia 1, and SAT (Southern African Territories) 1, 2, and 3. Within each serotype there is a large number of strains that exhibit a spectrum of antigenic characteristics; therefore, a number of vaccine strains for each serotype, particularly O and A, are required to cover antigenic diversity.

Transmission of FMD is generally by contact between susceptible and infected animals. Infected animals have a large amount of aerosol virus in their exhaled air, which can infect other animals via the respiratory or oral routes. All excretions and secretions from infected animal contain virus and have a remarkable capacity for remaining viable in carcassses, animal by-products, water, straw bedding and even in pastures. It is spread by direct contact, ingestion or inhalation. The virus can survive in dry fecal material for 14 days in summer, in slurry up to 6 months in winter, in urine for 39 days and on soil between 3 and 28 days.

Ruminants that have recovered from infection and vaccinated ruminants that have contact with live FMD virus can remain infected and carry the virus in the pharyngeal region for up to 2.5 years in cattle, 9 months in sheep and possibly lifelong in the African buffalo.

The primary site of infection and replication is usually the mucosa of the respiratory tract, although the virus can enter through skin abrasions or the GI tract. Replication then occurs in the local lymph node, and infection spreads via the blood stream to predilection sites in the epithelium of the mouth, muzzle, feet, and teats, and also to areas of damaged skin. Vessicles develop at these sites and rupture, usually within 48 hours. The viremia persists for at least 5 days.

The incubation period for FMD is two to fourteen days, depending upon the infecting dose, susceptibility of the host and strain of the virus. After the incubation period, a fever of up to 106°F (41°C) develops, the animal is anorectic and salivates and stamps its feet as vesicles develop on the tongue, dental pad, gums, lips, and on the coronary band and interdigital cleft of the feet. Vesicles may also develop on the teats and udder, particularly of lacting cows and sows, and on areas of skin subject to pressure and trauma, such as legs of pigs. Young calves; lambs, kids, and piglets may die before showing any vesicles because of virus-induced damage to the developing cells of the myocardium. Vesicles in the mouth, even when severe, usually heal within seven days, although recovery of the tongue papillae takes longer. Lesions on the mammary gland and feet frequently develop secondary infections, resulting in mastitis, underrunning of the sole and chronic lameness. In pigs, the complete horn of the toe may be lost. Cattle and deer may also lose one or both horns of the foot.

In cattle and pigs, the clinical signs of FMD are indistinguishable from those of vesicular stomatitis and vesicular exanthema.

Mortality is low, but the economic losses are catastrophic because of the strict quarantine and eradication programs. United States has a policy of slaughtering of all affected and in-contact susceptible animals and strict restrictions on movement of animals and vehicles around infected premises. After slaughter, the carcasses are either burned or buried on or close to the premises, and the buildings are thoroughly washed and disinfected with mild acid or alkali and by fumigation. Because of the sensitivity of the virus to acid and alkaline pH, sodium hydroxide, sodium carbonate, and citric or acetic acid are effective disinfectants.

Control is by movement restriction, quarantine of affected premises, and vaccination (last option) around the affected premises. FMD vaccine is a killed preparation and at best, affords good protection against challenge for four to six months. The antigenic diversity of strains of FMD virus within each of the serotypes is an additional complication, so it is necessary to ensure that vaccines contain strains antigenically similar to the potential outbreak strains.

Anthrax is an acute, serious infectious febrile disease of virtually all warm-blooded animals, including man and occurs naturally in animals in South Dakota, Nebraska, Arkansas, Mississippi, Louisiana, Texas, and California.

Anthrax is a disease caused by a spore-forming bacteria called Bacillus anthrasis and after the bacilli have been discharged from an infected animal or exposed to oxygen from an opened carcass, they form spores that are resistant to extremes of temperature, chemical disinfectants, and desiccation. For this reason, the carcass of an animal dead from suspected anthrax should not be necropsied.

Bacillus produces an edema toxin and a lethal toxin. Both toxins, gain entry to target cells by competitive binding with a third protein, protective antigen, that has a membrane translocation function. The toxins and the capsule are the primary virulence factors of the anthrax bacillus.

Outbreaks of anthrax commonly are associated with neutral or alkaline, calcareous soils that serve as incubator areas for the organisms. In these areas, the spores apparently revert to the vegetative form and multiply to infectious levels when environmental conditions of soil, moisture, temperature, and nutrition are optimal. Cattle, horses, sheep, and goats may readily become infected when grazing such areas.

During an epidemic, flies and other biting insects may mechanically transmit the disease from one animal to another, but this mode of transmission is of minor importance. Infection also may be caused by consumption of contaminated feedstuffs, eg, meat and bone meal. Occasionally, crops such as hay grown on contaminated soil have caused small outbreaks. Pigs, dogs, cats, mink, and wild animals in captivity have acquired the disease from consumption of contaminated meat.

The incubation period is three to seven days and the clinical course of the disease ranges from peracute to chronic. The peracute form is characterized by sudden onset and a rapidly fatal course. Staggering, dyspnea, trembling, collapse, a few convulsive movements, and death may occur in cattle, sheep, or goats without any previous evidence of illness.

In acute anthrax of cattle and sheep, there is an abrupt rise in body temperature and a period of excitement followed by depression, stupor, respiratory or cardiac distress, staggering, convulsions, and death. There may be bloody discharges from the natural body openings.

Chronic infections are characterized by localized, subcutaneous, edematous swelling that can be quite extensive. Areas most frequently involved are the ventral neck, thorax, and shoulders.

Rigor mortis is frequently absent or incomplete. Dark blood may ooze from the mouth, nostrils, and anus with marked bloating and rapid body decomposition. The blood is dark and thickened and fails to clot readily. If the carcass is inadvertently opened, septicemia lesions are seen. Hemorrhages of various sizes are common on the serosal surfaces of the abdomen and thorax as well as on the epicardium and endocardium. An enlarged, dark red or black, soft, semifluid spleen is common. The liver, kidneys, lymph nodes usually are congested and enlarged.

Anthrax must be differentiated from other conditions that cause sudden death. In cattle and sheep, clostridial infections, bloat, and lightning strike may be confused with anthrax.

A confirmatory laboratory examination should be done by collecting a small amount of blood from a superficial vessel such as the jugular vein. Before submission, the laboratory should be contacted to determine appropriate shipping procedures.

Anthrax in livestock can be controlled by annual vaccination of all grazing animals in the endemic area and by implementation of control measures during outbreaks. Vaccination should be done two to four weeks before the season when outbreaks may be expected.

Specific control procedures are necessary to contain the disease and prevent its spread. These include:
     1. Notification of the appropriate regulatory officials and your veterinarian;
     2. Rigid enforcement of quarantine;
     3. Prompt disposal of dead animals, manure, bedding, or other contaminated material
         by cremation or deep burial;
     4. Isolation of sick animals and removal of well animals from the contaminated area;

5. Disinfecting of stables, pens, milking barns, and equipment used on livestock;

6. Use of insect repellents;

7. Control of scavengers that feed on animals dead from the disease;

8. Observation of general sanitary procedures by people who contact diseased animals.

Anthrax in humans is rare. Most cases develop in people whose occupation place them in close contact with livestock or the contaminated products of livestock such as wool, goatskin, and pelts. Direct human-to-human transmission of anthrax is extremely unlikely, and most experts question whether it is possible.

Three types of anthrax are seen in people: cutaneous (skin), intestinal, and inhalation. The incubation for the disease is approximately two to seven days.

In people, cutaneous anthrax accounts for about 95% of all natural infections and develops when the anthracis bacteria enter the skin through cuts or abrasions. Without antibiotic therapy, the death rate from cutaneous anthrax is approximately 20%; if appropriately treated, death is rare.

Intestinal anthrax results from consumption of contaminated and undercooked meat. Affected individuals may experience nausea, inappetence, vomiting, and fever, followed by abdominal pain, blood in the vomitus, and severe diarrhea. Mortality is estimated at 25-75%. Human intestinal anthrax has not been reported in the United States during the 20^th and 21^st centuries.

Inhalation anthrax may initially present as a flu-like illness. A short period of improvement may follow, after which the patient rapidly deteriorates with high fever, respiratory distress, and shock. Fatalities approach 95% if not treated within the first 48 hours.

Infection can be prevented and treated with antibiotics. Because the course of the disease is rapid, prompt administration is essential. Effective antibiotics include ciprofloxacin, doxycycline, and amoxicillin. Vaccination is effective at preventing infection in animals and people. Animal vaccines have not been approved for and should not be administered to humans. A vaccine is available for humans, but population-wide vaccination in the United States has not been recommended because risk has been considered low.

Vesicular Stomatitis (VS) is a viral disease of cattle, swine, and horses and characterized clinically by the development of vesicles of the mouth, feet, and teats. On occasion this infection occurs in man as an influenza-like disease. This sporadic, re-emerging viral disease is endemic in the warmer regions of the Western Hemisphere and in the United States it’s mostly in the Southwest.

Aside from its negative economic impact on livestock, VS is significant because of its outward signs are similar to foot-and mouth disease (FMD).

Vesicular Stomatitis is caused by two distinct rhabdoviruses designated as the New Jersey and Indiana types. The New Jersey type is the most common isolated. How VS spreads is not fully known; insect vectors, mechanical transmission and movement of animals may be responsible. Once introduced into the herd, the disease moves from animal to animal by contact or exposure to saliva or fluid from ruptured blisters.

Clinical signs include vesicular lesions on the tongue, oral mucosa, teats or coronary bands of the feet, fever, drooling or frothing at the mouth. Oral lesions can be so painful that animals refuse to eat or drink resulting in severe weight loss. Foot lesions can also result in lameness.

The only way to diagnose and differentiate VS from FMD is through laboratory tests. Suspected cases should immediately brought to the attention of state or federal authorities.

No control measures are taken eventhough there is a vaccine available in some countries of the American tropics. Since it is a self-limiting, non-fatal viral disease, treatment is also not usually undertaken. The systemic effects of the viral infection are non-responsive to therapy and the local lesions in the mouth or on the feet or udder also usually heal without any therapeutic intervention. Maintaining the affected animals in a hygienic environment is recommended to prevent secondary bacterial infection.

References

The Merck Veterinary Manual, Eighth Edition, CD-ROMÓ2000, Merck & Co., Inc.
Generalized Conditions; Foot and Mouth Disease; Anthrax; Vesicular Stomatitis;

USDA Web site:
www.aphis.usda.gov/oa/fmd/index.html

Cornell Web site:
http://www.4law.cornell.edu/uscode/21/134a.html

Texas Animal Health Commission:
www.tahc.state.tx.us

National Cattlemen’s Beef Association:
www.beef.org

Humanitarian Resource Institute:
http://www.humanitarian.net/biodefense/ukfmd2002.html

American Veterinary Medical Association

Anthrax Fact Sheet 10/12-2001

Texas Cooperative Extension Service, The Texas A & M University System, College Station, Texas. Official Dept. of Defense web site for Anthrax

www.anthrax.osd.mil

Centers for Disease Control

www.cdc.gov/

Johne’s Disease

2001-03-01T13:39:00.000-08:00

Introduction:
The field of communication is on the threshold of an electronic explosion that is putting a large amount of information into our learning library.
For many years, I have written articles for veterinary and lay journals and magazines; however, due to today's mode of communication through computers and Internet, this will be my first Internet newsletter.
A quarterly newsletter will allow me to align with the seasons (Summer, Fall, Winter, Spring). Special updates will be written as needed.
Everyone has different needs and/or concerns. I do not have all the answers but will possibly know someone that can help find the answer; therefore, please e-mail me at dbechtol@paloduro-consulting.com with your questions, needs and/or concerns.
Current diseases of concern for my clients and me are:
     Johne's Disease and
     Mycoplasmosis.
Johne's Disease
Johne's disease was identified more than a century ago, yet remains a common and sometimes costly infectious disease of dairy cattle that has been documented in beef herds throughout the U.S.
The Beef 97 Study, a recent project by the USDA's National Animal Health Monitoring System (NAHMS), showed that 92.2 percent of beef producers were either unaware of Johne's disease or recognized the name but knew little else about it.
Johne's disease typically starts as an infection in calves, though clinical signs do not generally appear until cattle are 2 to 5 years of age. The infection is difficult to detect in its early stages and there is no cure once an animal becomes infected.
While this is a complex disease that we do not completely understand, basic information is available about the bacteria that causes the disease, how it is transmitted and how to control it.
Johne's disease results from infection with bacteria called Mycobacterium paratuberculosis. This organism grows very slowly, causes a gradually worsening disease condition, and is highly resistant to the infected animal's immune defenses. Infected animals may therefore harbor the organism for years before they test positive or develop disease signs.
The bacteria primarily infect the intestine, leading to prolonged diarrhea, poor digestion, and excessive weight loss. These bacteria are typically shed, in varying numbers, in an infected animal's feces. Once outside the animal, the bacteria no longer multiply, however they are quite hardy, living for months in water, feed, and manure. Susceptible, non-infected animals may pick up the bacteria through fecal contaminated feed or water. These newly exposed animals may develop disease and spread it within the herd.
Calves less than 6 months old are most vulnerable to infection. Under intensive housing conditions with a high level of exposure of young cattle to the organism, clinical Johne's disease can become common in cattle from one to three years of age.
Contrary to earlier notions that fecal contamination of feed and water was the sole means of transmission, infection of calves before they are born is possible. Fetal infection can occur in 20 to 40 percent of calves from infected cows showing clinical signs and about 10 percent of calves from infected cows not showing clinical signs.
DiagnosticsBoth fecal culture and blood serum antibody tests are available to producers to determine the disease status of a herd or an animal. Both tests fail to detect early infections because blood antibody development and detectable fecal shedding do not usually occur until late in the course of the infection. However, informed use of tests along with a history of clinical signs of disease in the herd can provide information to assist disease management in the individual cow and the herd.
Control
Principles of Johne's disease control include:
     Reducing exposure and infection of replacement cattle
     Identifying and removing the most highly infected cattle, and
     Preventing introduction of infection by screening sources of replacements.
Johne's disease control programs require a long-term commitment to prevention and must be adapted to individual herds.
Additional sources of information include
     Your local veterinarian
     USDA:APHIS Info Sheet August 1999(referenced for this newsletter)
     Johne's Information Center on the World Wide Web at http://www.aphis.usda/vs/ceah
     (For Johne's disease information, see the Center for Animal Health Monitoring then the Dairy Cattle or Beef Cow-calf pages.

Mycoplasma Bovis
Mycoplasma infections seem to be the "buzz" word or concern in my practice at this time.
Dr. Ricardo Rosenbush of Iowa State University presented a paper to the Academy of Veterinary Consultants " Should Mycoplasma Bovis Be A Concern in Feedlots" and I will be using his presentation as one of the references.
This infection, caused by Mycoplasma bovis, can have a variety of clinical signs. Pneumonia and arthritis are important clinical signs for feedyards, but we shouldn't necessarily assume that you have to have both pneumonia and arthritis to have a M. bovis infection. Many times we see pneumonia as the only presentation. In one disease outbreak at Agri Research Center, there were 21 deads from respiratory clinical signs only with Mycoplasma being isolated from 12 of the 21 head.
Outside of feedyards, mastitis is also an important disease caused by M. bovis and calves from these dairy herds may end up fed in feedyards.
Skin abscesses according to Dr. Rosenbush may also be seen.
Middle ear infections (Droopy Ear Syndrome) tend to be a significant problem in lighter calves after a high morbidity/pull rate has occurred.
What seems to be the most significant cause of concern is the lack-of response to antibiotic therapy. Different types of antibiotic therapy programs have been used with striking unresponsiveness. At necropsy multiple abscesses are noticed which tend to be distributed at the cranial aspect of the lung. (See figures 1,2, 3)

1.Mycoplasma abscesses

2.Pasteurella fibrinous pleuritis

3. Haemophilus fibrin

Also at necropsy, the joint capsule would be thickened but otherwise be unremarkable; however, the synovial sheaths and the areas above the joint are enlarged with both excess fluid and the presence of abscesses similar to those seen in the lung. The joint fluid is usually clear whereas with Haemophilus arthritis the joint fluid is purulent.
DiagnosticsWhen dealing with pneumonia and arthritis, the best diagnostic method is a lung-tissue submission.
As of today, in the United States it's not possible to use serology to control M. bovis outbreaks in feedyards because of all the false positives without the actual disease being present.
VaccinationThere is no licensed vaccine in the United States; however, there is activity in autogenous bacterins with sporadic to questionable results.