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Problem Topic Sheets - 1998 Herd Production Medicine

Last Updated  08/22/99  JM Gay 3/98

Objectives: For you think about the herd aspects of the problem that you select in all of its dimensions and complexity, organize a logical approach to that complexity and, in the process, learn a lot about that problem.

Goal: A concise, logically organized several page guide for the practitioner and fellow students. Assume that the audience for these is reasonably familiar with the topic from an individual animal perspective but is almost completely unfamiliar with the topic from a herd perspective and has limited time to spend learning about it.

Focus: The veterinarian's role in detecting, solving, managing and preventing problems, including a hierarchical approach to monitoring procedures, in groups of livestock beyond that in the individual animal. Target northwest herds in terms of nature of the problem, management, housing and diet.

Outline of Topic Sheet:

Remember that the following outline suffers from my attempt to generalize it to all herd situations, which range from endemic to epidemic outbreaks of infectious disease problems, production diseases such as displaced abomasums or hypocalcemia, prevention as well as detection and control, and suboptimal production problems such as low conception frequency or low production. Thus, not all of the following questions or points may be relevant to a particular problem and other important questions may be missing.

For uniformity of appearance, please use the following headings in your topic sheets.

  1. Problem Name:
  2. (See examples below)

  3. Synopsis:
  4. A brief, concise description of the different manifestations of the problem in herds, its between herd (what proportion of herds are affected?) and within herd prevalence (what proportion of animals at risk within a herd are affected?) including typical clinical to subclinical ratios, major risk factors, biological pathways and mechanisms. Focus on those items related to controllable risk factors, critical control points and interventions.

    How is the problem typically manifested? What are the management target values (what should we aim for?) and what are the alarm values (at what levels should we initiate a special investigation?)? What are the major risk factors for the problem, especially those directly under management control?

    You may wish to create a diagram showing the causal relationships and pathways.

  5. Economic Impact and Intervention Cost-Benefits:
  6. The forms of economic impact are usually 1) lost production, 2) reduced herd longevity, 3) reduced salvage value, 4) treatment costs, 5) prevention costs, and 5) death loss. What is the economic justification for the producer to control or prevent this problem in their herd? This is crucial information. Industry-wide loss estimates are useful for policy makers but not for decisions at the herd level. How much does the problem typically cost per affected animal? Because prices vary, this is best stated in the units of production (e.g. lbs. of milk, lbs. of gain, no. of calves weaned). What are the costs and benefits of potential interventions? How much does it typically cost per affected animal in the subclinical and in the clinical forms? How sound is this evidence?

  7. Herd Problem Workup Strategy:
  8. If a herd is in a crisis, what is the logical hierarchy of steps steps to diagnosing and solving the problem? What are the potential risk factors? How are the potential risk factors that are causing the problem in that particular herd discriminated from those that are not? What previous performance data is useful? How can information from this data be generated, particularly in the absence of a good production accounting system with complete records? Which animals and how many should be examined (if any)? What parts of the livestock premises, management or diet? What tests if any should be done? What are the costs of these? If specialized tests are required, who performs them and how can they be contacted? How do these tests perform in an outbreak situation in terms proportions of true positives, false positives, true negatives and false negatives? How do they perform in an endemic situation with a high proportion of subclinically affected compare to clinically affected animals?

    You may wish to diagram the logical approach to the workup as a tree, the branches dependent on what you find at each decision point.

  9. Herd Problem Prevention:
  10. What are the management procedures necessary to prevent the problem? How strong is the evidence for these (e.g., based on valid scientific studies, subjective observation, or conjecture)? What is the optimal prevention strategy or strategies? What is the cost-benefit of these? If procedures such as vaccination are available, what is the efficacy of these? Are these based on randomized controlled field studies?

  11. Herd Monitoring Procedures:
  12. What should be monitored to determine if control or prevention procedures are functioning sufficiently to minimize economic losses from the problem? How strong is the evidence for the efficacy of these? What is the logical hierarchy of the best monitoring strategy? What is the cost of the monitoring procedures versus the value of the information gained? If special software or equipment is required, what does it cost and where can it be obtained?

    You may wish to diagram the logical monitoring hierarchy as a tree, the critical control points with the broadest coverage being nearest to the trunk and the underlying critical control points being more distant branches.

    If individual testing is involved, how many individuals in an at-risk group should be tested? How frequently? How do these tests perform in a monitoring situation in terms proportions of true positives, false positives, true negatives and false negatives? How strong is the evidence for the validity of the tests? What is the cost of this testing versus the value of the information gained?

    If the problem is infectious, what is the optimal method of certifying that the herd is free from the infection?

    What are the critical control points for the problem? How can they be monitored efficiently and economically?

  13. Specialized Skills, Knowledge and Equipment:
  14. What special skills or techniques are needed by the veterinarian to carry out either diagnostic work-up or ongoing monitoring procedures? Where and how can the practitioner learn these skills? What are the key literature and internet references for these?

    What equipment is needed? What does this cost and where is it obtained (include address and phone number of manufacturers if not readily available)?

  15. Annotated Bibliography:
  16. A carefully selected set of the best internet materials, papers and book chapters on the problem that if read will enable the practitioner to answer in the shortest time the above questions and to motivate their client. Include a short summary of the essential information in each and a succinct evaluation of the strength of evidence of each. Is it based on valid scientific evidence or less strong evidence? Internet materials are especially valuable for practitioners because they are immediately available at no cost. However, they can also vaporize in an instant. Journal papers are the next best because they can be faxed from libraries within several days of request but at a cost. Books must be purchased, are usually not current even at the time of publication (due to the time lag between the writing and the publishing) and may have gone out of print.

  17. Names of Resource People:
  18. A list of currently active practitioners, academicians, extension personnel, private consultants and others with special expertise on the topic as evidenced by their publications, public presentations or consulting activity.

  19. Other References:

Cite all other sources used to answer the above questions, using a citation style similar to JAVMA's for the references. To avoid the necessity of renumbering when references are changed or moved in your text, I recommend that you use the (author, year) style in the text and order your reference list alphabetically by author's last name. The purpose is to provide more background material for those who want to dig deeper than the annotated bibliography and to enable them to check the sources of your statements. Provide URL's for any relevant materials that are located on the Internet.

Procedure and Timelines:

I intend that this be a group project that everyone participants in and that everyone benefits from. The primary group will be responsible for authoring the topic sheet. Everyone else will provide feedback to the authoring group on the first and second drafts. I will grade the final draft. My primary objective is to have you think about the herd aspects of the problem that you select in all of its dimensions and complexity and that you organize a logical approach to problem workup and knowledge.

First Step:

Select a major problem affecting a type of operation that involves herd monitoring and veterinary interventions to solve production and management problems in a group of animals. The following is certainly only a partial list. Although you are free to propose a variation on any of the following or one that isn't on the list, be sure to okay it with me before getting too far into it.

With each problem are some focus questions or points intended to get you started thinking about the problem. These are not exhaustive and do not necessarily identify all the important dimensions of the problem that are important to consider.

General Examples:

BVD herd problem detection, management and prevention

"How do I get it out of a herd once it is there? What tests do I use on which animals already in the herd how often? How do I keep it out? Which vaccines do I use, if any, on what schedule given to which animals? What procedures do I use on incoming animals to prevent re-introduction?"

Johne's disease detection, management and prevention

"How do I go about getting it out of a herd? Do I test and, if so, with which test on what animals how often? What are the benefits and pitfalls of testing? How do I resonably certify that a herd is disease-free? What management practices will enhance herd biosecurity, with respect to both introduction into the herd and transmission within the herd?"

Dairy Examples:

Declining or low (compared to industry targets) per cow per day milk production

Transition cow feeding and grouping management to minimize endemic problems of hypocalcemia, lactic acidosis, ketosis and displaced abomasum.

NEFA's, rumenocentisis, MUN's, urine pH, balancing forage macrominerals, body condition scoring and management, ration balancing and feed delivery management, forage particle length analysis

Cow comfort

Stall design with dimensions, bedding material selection and management, feeding timing and management, cow flow at milking time, maximum standing time and maximum time away from feed and water for individuals, environmental factors (ventilation rates, temperature and humidity levels), alley and pen surfaces, recommendations on design specifications such space per cow, stalls per cow, lockups per cow, bunk space per cow, air exchange per cow, waterers per cow.

"How do I determine if cows are or aren't comfortable and if they aren't, how do I go about identifying what factors are causing the discomfort and then solving the problem?"

Contagious mastitis outbreak control and continual reduction of endemic infection (mycoplasma, S. aureus)

Milking time hygiene, bulk tank monitoring, milk quality maintenance, milking machine evaluation and monitoring

Environmental mastitis outbreak control and prevention

Milking practices, bedding type and management

Dairy calf BRD management and prevention

Colostrum management, housing, weaning and grouping strategies, selection and timing of vaccinations.

Beef Examples:

Declining or low (compared to industry targets) weaning weight per day of age

Perinatal calf mortality / weak calf syndrome

Weaning BRD management and prevention.

"What is the optimal weaning management program? What when?" Selection and timing of vaccinations is always a major question that producers ask.

Preconditioning for retained ownership through feedlot

"What is the optimal vaccination and management program for beef calves going to a feedlot?"


How do you detect the problem, how do you eliminate it and how do you prevent it?

Second Step:

Select your problem and your groups. By Tuesday, March 3rd, tell me what problem you are working on and who you are working on it with.

Third Step:

Begin by familiarizing yourself with the problem as described in major textbooks such as Smith Large Animal Medicine, Radostits Herd Health, Radostits Veterinary Medicine. Check for any relevant issues of Vet Clinic of North America. Identify the current major clinical papers by using Cornell Consultant. Using Medline, VetCD and the Guelph listing of table of contents, identify the relevant applied clinical papers dealing with the problem. Read through your selected papers, paying particular attention to answering the questions above. Identify the important aspects of the problem, particularly those things related to management.

If you find one or more papers that summarize most of the above information, verify the author's conclusions by checking the references in the paper as well as other references that you locate. In  your estimate, what is based on objective scientific evidence and what is based on subjective observation, hypotheses, and dogma? Sometimes the later is all we have but it is important to recognize when the supporting evidence we are using is weak.

If you can't find information that you need, state what is needed and why, and how you might go about determining it for individual operations (such as clinical trials).

Fourth Step:

First draft due by 5 PM Friday, April 3rd in with copies for the rest of the class in their mailboxes and to me either at my office (116S South McCoy) or in my mailbox in the VCS Department Office in McCoy Hall. Using the questions similar to the following, everyone in the class will review and provide comments back to the authoring group.

Overall, does this topic sheet provide me sufficient specific information and references to begin developing confidence to tackle problems of this nature in herds in the Northwest? Is the information specific enough? For example, is sufficient detail present that the reader could go to an affected herd and set up a successful monitoring program?

Is the causation evidence and the workup and monitoring approaches organized in a concise logical, hierarchical fashion? What important aspects of the problem are missing or don't receive sufficient emphasis? What statements may be in error? Of the above items, what needs to be developed further and what could be reduced? Was the search for relevant materials thorough? Are any important resources missing? Is the synopsis consistent with these materials? Does it resolve areas of disagreement between the resources?

Another question for guidance is "Is this of sufficient quality that it could be published in The Bovine Practitioner?" If not, why not? For a senior paper?

Fifth Step:

Comments provided back to the authoring group by everyone in the class on Tuesday, April 7th.

Sixth Step:

Second draft is due on 5 PM Friday, April 17th to classmates and to me, along with a disk copy that includes one of the group's e-mail address and is in a format that is in or will translate to Microsoft Word 7.0. I will convert these to RTF (Rich Text Format) and will load them onto the class Internet website using Microsoft Frontpage. At that time, I will invite comments from bovine practitioners and academic clinicians. If you are concerned about this aspect, please discuss your concerns with me.

Seventh Step:

Comments returned to groups by Tuesday, April 21st.

Eighth Step:

Final draft incorporating suggestions from the website is due in class on Tuesday, April 28th, along with 1) final copies for evaluation by the class, 2) a disk copy as above for final posting on the website and 3) copies for me of the comments that you received via e-mail.

Ninth Step:

Final evaluation and grading of topic sheet. The evaluation will be along the lines of the questions in the fourth step.


Your input, comments and questions are welcome at anytime in person in my office (116S South McCoy), in class, via e-mail or by telephone. If these dates conflict with other major events, such as exams, please let me know what date will work better. If I can help you with any part of this assignment, don't hesitate to ask.


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