Not everything a vet tells you is a certainty. We don’t lie, of course, but sometimes we must make educated guesses based on limited evidence or even our own experiences. This isn’t necessarily bad medicine or even risky, but there may be a better way to approach problems. How different vets deal with difficulties has resulted in a debate between how we approach veterinary medicine; the debate between evidence-based veterinary medicine and experience-based veterinary medicine. 

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Experienced-Based Veterinary Medicine

Experience-based veterinary medicine, sometimes termed eminence-, anecdotal- or opinion-based veterinary medicine, is medicine primarily driven, as the name suggests, from previous experiences without direct backing from scientific evidence. Before large scale scientific studies and easily-accessible evidence, this was what most medicine was based on. A doctor or vet would make a decision based on their prior experience, their perceived knowledge and what they thought was best at the time. This trial and error approach undoubtedly works for many simple cases but has a number of flaws.

Firstly, just because something works in many cases, does not mean it works in every case

By only using prior experience of similar cases, and not considering the individual, that 1% can be misdiagnosed or mistreated. Similarly, just because something works, does not make it the best option – relying on experience too much can result in clinicians becoming stuck-in-their-ways and not looking for new, potentially better ways, to do something. It also tends to result in more learning from mistakes – while learning from mistakes is always important, when a patient’s life is at stake, then getting it right initially can be important. Relying on experience can also lead to discounting of evidence even when presented properly, or the opposite: misreading certain information and taking it as hard facts. It is not that difficult for anyone to say something and claim it is fact, and relying on this sort of ‘evidence’ can result in poor medicine. 

That isn’t to say that experience is not valuable 

If a person has done a thousand cat spays, they probably know a thing or two about spaying cats, compared to someone who has done a lot of reading but has little practical experience on the matter. We do not want to downplay older and more experienced clinicians who have years of practice under their belt. But it is important for every vet, old and new, to know that knowledge is always changing and people must change too. 

Evidence-Based Veterinary Medicine?

This brings us to evidence-based veterinary medicine, or EBVM. EBVM is the practice of using the most relevant and best evidence, individual patient circumstances and clinical expertise to make a decision. This requires a vet to have a good understanding of how to find evidence, appraise it for relevance, quality and reliability, and apply it to the current situation. EBVM is currently being introduced to veterinary schools around the country, so newer vets are more likely to have formal training in it (we were studying it 20 years ago… young vets today harumph harumph… 😉 – Editor). Evidence-based practice is also a key component of other industries, such as human medicine, aeroplane piloting, and law. 

To approach a decision using EBVM, a vet will first have a question to answer 

For example – how do I diagnose this disease? What can I treat this with? How likely is it to work? Where a purely experience-based approach may just rely on past knowledge or a guess, EBVM builds upon this experience and looks for information in scientific literature. The best evidence is formal scientific reviews that have been independently appraised – these are collections of various studies that have been reviewed for their information to try and answer a question using as much evidence as possible. Less reliable is individual papers and non-appraised studies. At the bottom of the “acceptable evidence” pile are ‘expert’ opinions, below which are personal ideas and anecdotes. EBVM should be primarily looking at evidence from the first categories.

Even if the evidence has been appraised already, a good clinician should then appraise it themselves – is it relevant to the question, is it reliable, does it help? The evidence is then applied to the situation. Finally, EBVM requires a clinician to evaluate the performance – did the evidence work? Why or why not? What can be done differently? Was the evidence lacking or not appropriate?  This is the best approach to all veterinary medicine problems. 

EBVM is not perfect, and will not result in a positive outcome every time 

This is why evaluation afterwards is important. EBVM can also sometimes be difficult to do properly due to a lack of evidence, lack of time to evaluate evidence, lack of training on proper EBVM, poor quality evidence, or evidence that is useful for clinical studies but not day-to-day in a veterinary practice. In these situations, clinicians may tend to fall back on prior experience or skip steps in EBVM.

Example EBVM Case:

Let’s take an example. A dog presents with diarrhoea. An experience-based clinician may say that antibiotics usually fix diarrhoea, so they try those. It may even work. But this is not proper EBVM. A clinician using EBVM will ask “what is the best treatment for simple diarrhoea?” and start researching, preferably for scientific literature reviews and papers. They find some on the use of antibiotics vs anti-inflammatories, a paper on antibiotics in cats, two websites selling antibiotics, and a website with an article called ‘why antibiotics in dogs are overused’. 

Now they have found evidence, they must appraise it

Good clinicians should always consider where the evidence came from, who posted it and why, and whether the testing methods were reliable. Straight away, the websites can be discounted as an impartial source – although they may have useful information, there is bias. They are trying to sell antibiotics, so of course they will claim they are useful to cure diarrhoea.

Similarly, the article can be downgraded. It was written by a vet with a lot of letters after their name, but they haven’t provided many sources – this is an opinion piece and may not be reliable evidence. It could be biased too. The paper on antibiotics in cats is peer reviewed with lots of sources and evidence, but of course is not relevant to dogs, so can be demoted too – while the ideas may be useful, it isn’t clear whether or not it applies to dogs. The other papers on antibiotics vs anti-inflammatories seem more relevant, and the studies have been peer reviewed. The clinician looks over them briefly and their methods are appropriate. Sadly, they cannot find a literature review of antibiotic use in dog diarrhoea – this would be the best evidence. 

Now they combine that information with all the other factors in the case

With the information they have, the owner’s financial and home situation, and the individual dog, they determine that actually antibiotics do not cure diarrhoea as much as the other vet claims and are not the best practice for treating diarrhoea. Instead, they opt for anti-inflammatories, as the evidence suggests. The clinician observes the response and reviews it for next time. It, of course, becomes experience, but this does not mean that the evidence will always say anti-inflammatories are best. A good vet knows to regularly review what they think they know, in case new studies reveal new information that could improve their clinical decision making.

What is Best? Is There a Role for Both Approaches?

We hope that it is pretty clear by now that EBVM should be at the forefront of all clinical decision making for vets. Ensuring that a vet is equipped with the most up-to-date knowledge and can apply it properly helps advance the care they can offer, reduce the risk of mistakes and improve success rates. 

This does not mean experience is useless or should be frowned upon. Far from it. Instead, experience should be used as a foundation for EBVM by assisting vets with finding evidence quickly and putting it to use. Rather than detract from EBVM, experience enhances it. 

There is a role in veterinary medicine for both evidence and experience, but a vet should always be prepared to be proven wrong, correct mistakes, learn new things and put them to good use, so the field – and therefore the care we can offer your animals – grows ever stronger.

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