Evidence-Based Veterinary Medicine: What is it & Why Does it Matter?

The Equine Veterinary Journal and Equine Veterinary education journal have just launched a new open-access evidence-based medicine resource, including systematic reviews, critically-appraised topic reports (CATs) and editorials. This includes my most recent editorial on the subject, which I can now share here since it is an open access publication:

McKenzie, B. (2014), Evidence-based veterinary medicine: What is it and why does it matter?. Equine Veterinary Education, 26: 451–452. doi: 10.1111/eve.12216

The term ‘evidence-based medicine’ (EBM) began to appear in the human medical literature in the early 1990s. Since then, both the term and approach have become ubiquitous in human medicine. Although there has been controversy and debate about EBM, it has been widely adopted and almost universally endorsed by medical associations, specialty boards, patient advocacy groups and government agencies (Claridge and Fabian 2005).

References to ‘evidence-based veterinary medicine’ (EBVM) did not become common until nearly 10 years later. The term is now widely used, and references to EBVM are common in veterinary journals and continuing education meetings. However, the principles and practices of EBVM have not yet been endorsed or employed widely in veterinary medicine (Vandeweerd et?al. 2012).

Like other advances in human medicine, EBM must be adapted to meet the unique and varied needs of veterinary practitioners. However, once properly ‘translated’ into veterinary medicine, EBVM offers many benefits to veterinarians and our patients and clients.

What Is It?

At its heart, EBVM is the formal application of the philosophy and methods of science to generating knowledge and making decisions in veterinary medicine. As clinicians we need information to evaluate our patients’ health problems and provide effective preventative and therapeutic interventions. Evidence-based veterinary medicine provides tools and guidance to those who generate this information (through clinical research), those who disseminate it (through publication, continuing education, clinical practice guidelines, etc.) and those who utilise it (in clinical practice as well as public health and policy making). With better information and more efficient information management we are able to make better decisions and provide the best patient care possible.

Traditionally, veterinarians have relied on personal experience and the wisdom of mentors, teachers and opinion leaders to guide their clinical practices. Formal scientific research has played a role in informing clinical practice, but often the use of this resource has been inconsistent and indirect, filtered through the opinions of experts relied on by practitioners to interpret the scientific literature.

Evidence-based veterinary medicine is predicated on the understanding that this approach, which might be characterised as ‘opinion-based medicine,’ involves significant and predictable sources of error. Controlled scientific research effectively overcomes many of the limitations of individual judgement that lead us to the wrong conclusions and decisions.

Therefore, EBVM is partly a system for facilitating the effective use of controlled research to inform clinical practice. In addition to supporting the production of high quality research, EBVM promotes the dissemination of such research in a form which is practical and useful to clinicians. The scientific literature must be accessible to be useful, so EBVM proponents encourage open access publishing models. Since most clinicians lack the time and training to search and appraise the research literature personally, EBVM provides tools for synthesising this information in useful forms such as systematic reviews and clinical practice guidelines.

The main functions of EBVM are to facilitate the production of relevant, high quality scientific research, the effective dissemination of this research in a useful form and the integration of this information with clinical experience, client goals and values and the unique circumstances of each individual patient in order to inform decision-making and optimise patient care.

Why Does It Matter?

There is a robust literature evaluating the causes of error in clinical decision-making by physicians. This literature shows that the most significant sources of error are precisely those EBVM is designed to mitigate: the limitations of individual perception and judgement and inefficiencies of traditional information management approaches (McKenzie 2014). The same limitations and the same strategies for overcoming them likely apply to veterinary medicine.

Even the smartest, most highly trained clinician operates with all the limitations and quirks of the human brain. Science helps to compensate for these and improve the quality of the information available to us. Evidence-based veterinary medicine does not replace the judgement of the individual clinician. The practitioner is always the one to determine the information needed to help a particular patient, the relevance and reliability of the available scientific research and the best course of action within existing constraints, such as the interventions available, the values and resources of the client and other ‘real-world’ variables. However, ready access to relevant, high-quality scientific research supports the clinician in making the most effective diagnostic and therapeutic plan.

Evidence-based veterinary medicine also provides an approach to managing the information needed to make clinical decisions. The traditional approach is the ‘Just in Case’ model (Cockcroft and Holmes 2003). We endeavour to acquire and retain an enormous body of knowledge about health and disease and the interventions currently available just in case we need some of that information to help a given patient. This is an inefficient strategy that places a tremendous burden on the individual practitioner and provides much opportunity for error.

Evidence-based veterinary medicine promotes the ‘Just in Time’ model instead (Cockcroft and Holmes 2003). The clinician is trained to identify the information needed to manage a particular case and is given the tools and skills to locate that information and evaluate its relevance and reliability when it is needed. This reduces the cognitive burden on the practitioner and the opportunity for mistakes.

There is evidence in human medicine that both better information and more efficient information management provided by EBM improve patient outcomes and reduce medical errors and stress for clinicians (Bahtsevani et?al. 2004; Amarasingham et?al. 2009). Veterinarians and their patients would likely also benefit from wider use of these methods.

Finally, there is an ethical dimension to the use of EBVM. Of course, veterinarians are obligated to provide the best patient care possible and EBVM can facilitate this. However, there is also an ethical expectation that we should obtain informed consent from our clients before employing our interventions (Fettman and Rollin 2002). Such consent cannot be truly informed without explicit discussion of the uncertainties involved in a particular situation. Only through deliberate assessment and communication of the quality and limitations of the evidence for a particular intervention can we meet our obligation to properly inform our clients so they can make choices about the care we provide for their animals.

Evidence-based veterinary medicine provides practitioners with more useful and reliable information to support decisions, reduces error and stress, improves patient care and helps us meet our ethical obligations to our clients and patients. Evidence-based medicine is a well developed system widely employed in human medicine and, with appropriate adaptation, EBVM can be a similarly widespread and useful approach in veterinary medicine.


  • Amarasingham, R., Plantinga, L., Diener-West, M., Gaskin, D.J. and Powe, N.R. (2009) Clinical information technologies and inpatient outcomes: a multiple hospital study. Arch. Intern. Med. 169, 108114.
  • Bahtsevani, C., Udén, G. and Willman, A. (2004) Outcomes of evidence-based clinical practice guidelines: a systematic review. Int. J. Technol. Assess. Health Care 20, 427433.
  • Claridge, J.A. and Fabian, T.C. (2005) History and development of evidence-based medicine. World J. Surg. 29, 547553.
  • Cockcroft, P.D. and Holmes, M.A. (2003) Handbook of Evidence-based Veterinary Medicine, Blackwell Publishing, Oxford, UK and Malden, MA.
  • Fettman, M.J. and Rollin, B.E. (2002) Modern elements of informed consent for general veterinary practitioners. J. Am. Vet. Med. Ass. 221, 13861393.
  • McKenzie, B.A. (2014) Veterinary clinical decision-making: cognitive biases, external constraints, and strategies for improvement. J. Am. Vet. Med. Ass. 244, 271276.
  • Vandeweerd, J.M., Kirschvink, N., Clegg, P., Vandenput, S., Gustin, P. and Saegerman, C. (2012) Is evidence-based medicine so evident in veterinary research and practice? History, obstacles and perspectives. Vet. J. 191, 2834. doi:10.1016/j.tvjl.2011.04.013.
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