In the early 1990s, medical doctors began to explore the benefits of using peer-reviewed studies and the scientific process along with their clinical observations and experience to validate recommendations to patients. This practice rose out of the concern that too many decisions regarding patient care were based solely on historical practices and anecdotal reports. Leaders in the field began to encourage practitioners to review the scientific literature to locate peer-reviewed studies that could support their decisions. The practice of combining science and clinical experience is called “Evidence-based Medicine” or EBM.

We have these same issues in veterinary medicine and pork production. Too often we make decisions based on “the way we’ve always done it .” It’s easy to fall into the trap of shifting from one management program or treatment regimen to another based on someone’s perception of the potential outcome.

It is often impractical to conduct a controlled scientific study to accurately evaluate decisions in a pork production environment. Certainly, medical doctors face this same dilemma. After all, they cannot use their patients as subjects to evaluate treatment decisions. 

But we can review the scientific literature to determine if similar treatment regimens have been studied and what the outcomes were. Using this information, we should be able to offer the client a sound estimation of the likely outcome, given a similar situation. When scientific studies are lacking, other information sources, such as production records, can help validate suggested therapies or management changes.

Among the challenges we face in applying evidence-based decision making is access to the journals containing the scientific studies we wish to review. We and our clients tend to live in rural areas, often some distance from a technical library. While most journals are now accessible through the Internet, often only an abstract is available free of charge. A thorough literature review can become quite expensive if you have to order each article online. It’s time consuming and not a bill that most clients want to pay. 

An additional challenge is determining the quality and applicability of the information that you find. Is it a valid scientific study? What are the variables that may affect the outcome? Have those variables been appropriately addressed, and are there different variables on the farm that may influence the result?

The ability to accurately assess the scientific literature, or even promotional materials that a product salesperson provides, requires careful consideration and familiarity with the study’s design. What does the research really tell you that you can apply to the farm’s situation?  Do vaccine titers correlate with real-world efficacy?  Does pen gestation really improve sow well-being?

It is important to evaluate science and experience in the context of each other. By that I mean that either one alone can be misleading. Scientific studies are valuable to evaluate “treatments” in an environment that controls as many variables as possible, so that differences can be evaluated based on the application. These studies, however, may not translate well in the field because in a production environment you can’t control many of the variables. Likewise, field experience may be misleading. What may seem to be a response to a given treatment may simply be random chance or the difference observed may be insignificant. 

Bias is a real problem when evaluating scientific studies or clinical experiences. Whether intentional or not, we are all biased by our previous experiences and what we believe. When evaluating the validity of a practice or publication, it’s important that we determine if bias played a role in interpreting the results. Was there an attempt to eliminate biases in the study’s design?

In food-animal production we answer to many masters, including food safety, animal well-being, economics, veterinary responsibilities, trade implications and consumer perceptions, just to name a few. But it’s all the more reason to validate the decisions we make. 

The take-home message is to not discount experience but rather to augment it with a scientific-literature review, and critically evaluate both. Determine the applicability to the situation you are addressing. Evaluate the information quality based on the control of variables and bias, as well as the validity of the statistical analysis. Explore multiple sources of information and compare the results.

Evidence-based medicine benefits human doctors, and it can work for swine veterinarians.


If you want to learn more about EBM,check out “An Evidence-Based Approach to Production Medicine,” by M. Apley from the 2005 Proceedings of Iowa State University’s Swine Disease Conference for Swine Practitioners. Also, “Evidence-Based Medicine: How to Practice and Teach EBM,” 2000, 2nd Edition, New York: Churchill Livingston, by D.L.Sackett, S.E. Straus, W.S. Richardson, W. Rosenberg and R.B. Haynes.