What do Veterinarians Know About Nutrition?

It is not unusual for people promoting unconventional, approaches to pet nutrition, such as raw diets, grain free foods, homemade diets, a preference for organic ingredients, and so on, to dismiss objections to these approaches made by veterinarians. These people will often claim that veterinarians know little about nutrition and that what they do know is mostly propaganda fed to them by commercial pet food manufacturers. Like most bad arguments, this one contains a few bits of truth mixed in with lots of unproven assumptions and fallacies.

Most veterinarians do have at least a semester course on nutrition in general. And a lot more information on the subject is scattered throughout other courses in vet school. So the idea that we know nothing about the subject is simply ridiculous. However, it is fair to acknowledge that most veterinarians are not “experts” in nutrition, if by this one means they have extensive specialized training in the subject. The real “experts” in this area are board-certified veterinary nutritionists, individuals who have advanced residency training in nutrition and have passed the board certification exam of the American College of Veterinary Nutrition.

Of course, as I always take great care to point out, expertise is no guarantee of never falling into error, particularly expertise based primarily on experience and a familiarity with the opinions of other experts rather than solid scientific research. Given the limited research data available on many important questions in small animal nutrition, even the real experts are often forced to rely on extrapolation from basic science or research in humans and their own clinical experience, which are important sources of information but always less reliable than studies specifically designed to answer these questions. Nevertheless, boarded nutritionists have a legitimate claim to expert status in this area. And as a group, they generally are skeptical of many of the alternative approaches to nutrition, as they should be give the paucity of data to support them As for the question of the role of the pet food industry in veterinary nutrition education, there is some truth to the claim that much of that education is sponsored by companies who make pet foods. Obviously, most veterinary nutritionists put their training to work researching and evaluating food for veterinary species, so the money and expertise in this area tends to concentrate in industry. And it is not entirely unreasonable to ask the question whether or not this influences the information veterinarians get about nutrition. It quite likely does.

This is not the same thing as saying that veterinarians are all lackeys or dupes of industry and unable to think critically for themselves, however. I am generally as skeptical and critical of pharmaceutical companies and mainstream pet food companies as I am of herb and supplement manufacturers and producers of alternative diets. All of them have both a genuine belief (most of the time) in their products, a genuine interest in the welfare of the animals they serve, and a high risk of bias and cognitive dissonance that impedes their ability to see and accept the flaws in their own reasoning or the data that contradicts their beliefs.

One should always be aware of bias, but that awareness does not justify ignoring the arguments or evidence coming from a source with potential bias, only evaluating it carefully and critically. The reason science is so much more successful than unaided reasoning is precisely because it is a method for compensating for human biases and other cognitive limitations that interfere with our seeing the truth. Mainstream pet food companies undoubtedly have biases, but often they also have good scientific data, which is rarely available for the alternative products and approaches. Ignoring this data in favor of opinion, theory, or personal experience is not a recipe for improving the state of veterinary nutrition.

The real issue is not so much what do general practice veterinarians know about nutrition as what is the evidence supporting the alternative theories and products being promoted? The accusation that vets know little about nutrition, even if it were true, doesn’t invalidate their criticisms. The classis ad hominem fallacy is the strategy of attacking a person and imaging that somehow this attack says anything about that person’s argument. It is the mirror image, in many ways, of the appeal to authority fallacy, which involves claiming some special wisdom or expertise on the part of a person making an argument and then imaging that claim somehow proves the argument. If proponents of raw diets or other unconventional nutritional approaches wish to make a case for their ideas, they have to do it based on logic and facts, not on the presumed expertise of supporters or the supposed ignorance of critics. As always, it is the ideas and the data that matter, not the people involved.

That said, there is a certain hypocrisy to many of these criticisms in that they come from sources with no particular right to claim expertise in nutrition anyway. Proponents of alternative nutritional practices are almost never boarded veterinary nutritionists. Often they are lay people who have labeled themselves as experts without even the training general practice veterinarians have in nutritional science. And while they may not be influenced by the mainstream pet food industry, this only means they are less subject to that particular bias, not that they don’t have other biases. People selling pet food or books on veterinary nutrition are all too often blind to the hypocrisy of claiming their opponents are under the influence of pet food companies while ignoring the fact that they make money selling their own ideas or products.

Others who frequently claim most veterinarians know little about nutrition are themselves general practice veterinarians or specialists in some aspect of veterinary medicine other than nutrition. It may very well be true that they are well-informed about nutrition because they have an interest in it, but this is not evidence that their arguments are true and those of their opponents are false. It is not even evidence that they know more about nutrition than their detractors, who may themselves have studied independently in the area. If you’re not a boarded nutritionist, you can’t claim to be an expert. And whether or not you are an expert, your ideas must stand or fall on their merits and the evidence, not on any presumed superiority in your knowledge over that of your critics.

So I think it is fair to say that most general practice veterinarians have only a fairly general knowledge of veterinary nutrition. And it is fair to acknowledge that much of this information comes from a source with a significant risk of bias, that is the pet food industry. However, I see no evidence that proponents of alternative approaches to nutrition have a reason to claim they know more about nutrition than most veterinarians, or that they are free from biases of their own. Only boarded veterinary nutritionists can legitimately claim to be “experts,” and even this is no guarantee of perfect objectivity or the truth of everything they believe. Claims about who is or is not smart or informed enough to have an opinion on a subject are mostly a superficial distraction from the important elements of any debate, what are the arguments and data behind each position. Awareness of potential bias only serves to make one more careful and cautious in examining someone’s arguments and data, it doesn’t get one a free pass to ignore what they have to say.

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