Evidence-based medicine is key in achieving an ethical clinical practice

Surveys show clients expect to be told about the uncertainty associated with veterinarians’ recommendations

The relationship between evidence-based medicine (EBM) and ethics may not be immediately apparent. EBM focuses on facts and data, safety and efficacy, and determining what we do and don’t know. Veterinary ethics is about doing what is right or wrong in the context of veterinary practice. The values that inform ethical principles are subjective and not always shared among individuals or different segments of the profession. The evidence used to evaluate the safety and efficacy of medical treatments, in contrast, should ideally be produced by methods broadly agreed to be the most objective and reliable possible. However, EBM turns out to be a key tool for achieving ethical clinical practice.

Core principles, basic ethics

Despite inevitable controversy and disagreement, most veterinarians broadly accept some ethical principles. Some are articulated in statements such as the American Veterinary Medical Association’s “Principles of Veterinary Medical Ethics.”1 This document was adapted from the principles established for physicians by the American Medical Association, and veterinary associations around the world have adopted similar statements.2-6

Other widely accepted ethical standards are simply common elements of more basic cultural norms. For example, most of us would likely agree that we should try to help our patients and our clients, we should be honest with clients, and we should do our best to be technically competent and familiar with the current scientific knowledge that underlies clinical medicine.

These basic ethical precepts are formalized in the domain of medical ethics as several core principles, which usually include:

Beneficence – Clinicians should attempt to help their patients.7

Non-maleficence – Clinicians should attempt to avoid harming their patients or to do more good than harm.7

Autonomy – Patients (or, in veterinary medicine, their owners) have the right to accept or reject treatment. This is the foundation for the more specific concept of informed consent.7

Informed consent – Clients have the right to make choices about the treatment of their animals based on accurate, relevant information they can understand.8

The EBM piece

So what does EBM have to do with meeting these ethical obligations? Well, ethical judgements cannot be made without facts. The best path to abide by one’s ethical principles cannot be determined without an accurate understanding of the context. EBM informs ethical practice by giving us, and our clients, an accurate understanding of the risks and benefits of our actions as well as the degree of uncertainty about these.

In terms of beneficence and nonmaleficence, for example, one cannot successfully help patients and minimize harm without an accurate understanding of the causes of disease and the effects of our treatments. If we attribute illness to the wrong cause, we are unlikely to stumble across an effective remedy. And if our treatments don’t actually work, or if they have risks that we are not aware of, then we are less able to do good and avoid harm to our patients.

Tell clients the whole truth

Similarly, we deny clients their right to informed consent if we give them incorrect information about diagnosis, prognosis, or the likely outcome of our treatments. This is equally true whether we lie deliberately or are simply mistaken. The history of medicine is a long, frightening tale of incorrect beliefs about disease and of ineffective, even harmful, treatments enthusiastically applied by well-meaning doctors. We are no smarter or better intentioned than our predecessors, but thanks to science, we are better informed.

Evidence-based medicine, then, is arguably a necessary component to ethical veterinary practice. It provides clinicians with the most current and accurate understanding of the causes of disease and the risks and benefits of our therapies. Further, it helps us quantify the inevitable uncertainties we must accept and communicate to our clients.

There is rarely optimal evidence, so the most conscientious practitioner of EBM will often not be able to accurately predict the outcome of his or her treatments. However, even in this situation, EBM is useful because it supports truly informed consent. If the evidence supporting a particular therapy is weak, I may well still offer that therapy. However, I am able, even obligated, to understand the limitations of the evidence and share this with the client to help support informed decision-making.8

There is often anxiety among veterinarians about disclosing uncertainty to clients. We fear they may not trust in our competence or may eschew beneficial treatment if we express any uncertainty or discuss the limitations of our knowledge. However, there is evidence that may allay this anxiety. Surveys have shown that clients expect to be told about the uncertainty associated with our recommendations and that they do not lose confidence in us as a result.9 Even more significant from an ethical perspective, clients in one study emphasized that their central expectation for the information they were given by their veterinarians was that it be the truth.10 EBM helps us meet the ethical obligation and client expectation that we communicate truthfully about our recommendations and any of our uncertainties.

Entering contentious territory

So far, this idea that EBM can facilitate ethical veterinary practice by giving us the most accurate information and helping us measure our uncertainty may not seem especially controversial. Unfortunately, if we commit to EBM as the best source of information to support effective and ethical medicine, we eventually enter more tendentious territory.

For example, EBM includes the presumption that some sources of evidence are more reliable than others.11-12 This often leads to a conflict between what we believe, based on anecdote or personal experience, and what scientific evidence supports. Clinicians dislike being told that therapies that seem effective in use are either scientifically unproven or have significant evidence against their safety or effectiveness. Yet our obligation to be informed and competent, and to provide accurate and truthful information to clients, can sometimes mean accepting the unreliability of anecdotal experiences, even our own.

An even more contentious topic is the ethical appropriateness of theoretical systems and treatment methods with core principles that conflict with established science. Much of what is often called alternative medicine consists of beliefs about the causes of illness and methods of treatment that are either scientifically unproven or even demonstrably incorrect based on research evidence.13-14 Alternative medicine raises many complex ethical issues,15 and it has been argued, in both human and veterinary medicine, that the use and sale of such approaches, however honest and well-intentioned, violate some broadly held ethical principles.14-19

Informed consent and autonomy are denied when clients are given information about their animals’ health that is inaccurate by the best available standards of evidence and scientific consensus. Beneficence and nonmaleficence cannot be maintained if ineffective treatments are offered.16


Often, of course, there are legitimate disagreements about the meaning or strength of the evidence. However, there must be some generally accepted standard of proof required beyond simply the personal belief of the individual clinician to justify our treatments. If not, then there is no purpose to the systems of licensing and regulation intended to protect the public from unsafe and useless medical treatment. The caveat emptor free-for-all of medicine in the 18th and 19th centuries was ultimately rejected in the 20th as unsafe, and this was predicated on the belief that scientific evidence could provide a common basis for evaluating medical practice. This is a key pillar of the ethical structure of modern medicine, and EBM is an important tool for supporting ethical, science-based practice.


  1. ­­­AVMA Principles of Veterinary Medical Ethics. Available at bit.ly/1EvmrDs. Accessed 01-31-2018.
  2. AMA Principles of Medical Ethics. Available at bit.ly/2v5nkVX. Accessed 01-31-2018.
  3. CVMA. Principles of Veterinary Medical Ethics. Available at bit.ly/2JEZJyB. Accessed 01-31-2018.
  4. FVE. European Veterinary Code of Conduct. Available at bit.ly/2v7WnAU. Accessed 01-31-2018.
  5. AVA. Code of Professional Conduct. Available at ava.com.au/conduct. Accessed 01-31-2018.
  6. Veterinary Council of India. Code of Ethics. Available at tnsvc.org/forms/codeethics.pdf. Accessed 01-31-2018.Beauchamp TL, Childress JF. Principles of biomedical ethics. 5th Ed. (2001) New York, NY: Oxford University Press.
  7. Beauchamp TL. Childress JF. Principles of biomedical ethics. 5th Ed. (2001) New York, NY: Oxford University Press.
  8. Fettman MJ, Rollin BE. Modern elements of informed consent for general veterinary practitioners. J Amer Anim Hosp Assoc. 2002;221(10):1386-1393.
  9. Mellanby RJ, Crisp J, De Palma G, et al. Perceptions of veterinarians and clients to expressions of clinical uncertainty. J Small Anim Pract. 2007;48(1):26-31.
  10. Stoewen DL, Coe JB, MacMartin C, et al. Qualitative study of the information expectations of clients accessing oncology care at a tertiary referral center for dogs with life-limiting cancer. J Amer Vet Med Assoc. 2014;245(7):773-83.
  11. McKenzie B. A new perspective on evidence-based medicine. Vet Pract News. July, 2017. Available at bit.ly/2EGmn62. Accessed 01-31-2018.
  12. Cockroft, P. Holmes, M. (2003). Handbook of Evidence-Based Veterinary Medicine. Oxford: Blackwell.
  13. McKenzie, BA. Is complementary and alternative medicine compatible with evidence-based medicine? J Amer Vet Med Assoc. 2012;241(4):421-6.
  14. Ramey DW, Rollin BE. (2004). Complementary and Alternative Veterinary Medicine Considered. Ames: Iowa State Press.
  15. Nuffield Council on Bioethics. Complementary medicine: ethics. 2014. Available at bit.ly/2JGL327. Accessed 01-31-2018.
  16. Smith K. Against homeopathy-A utilitarian perspective.Bioethics. 2012;26(8):398–409.
  17. Ernst E, Cohen MH, Stone J. Ethical problems arising in evidence based complementary and alternative medicine. J Med Ethics. 2004;30:156-9.
  18. Milstein M. The case against alternative medicine. Can Vet J. 2000;41:769-72.
  19. Macdonald C, Gavura S. Alternative medicine and the ethics of commerce. Bioethics, 30: 77–84.

Dr. McKenzie discovered evidence-based veterinary medicine after attending the University of Pennsylvania School of Veterinary Medicine and working as a small animal general practice veterinarian. He has served as president of the Evidence-Based Veterinary Medicine Association and reaches out to the public through his SkeptVet blog, the Science-Based Medicine blog, and more. He is certified in medical acupuncture for veterinarians. Columnists’ opinions do not necessarily reflect those of Veterinary Practice News.

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