Herbs and Supplements for Pets: What Is a Vet to do?

I’ve written extensively about herbal remedies and dietary supplements both because these seem among the most likely to be useful of CAM therapies and also because they are widely used despite the lack of good evidence that they are safe and effective in most cases. The success of pharmaceutical medicines and vitamin supplements to treat deficiency diseases has created an expectation that taking a pill can have beneficial effects. When combined with the naturalistic fallacy (that we can identify some things as “natural” and then trust that these are safe) this predisposes people to believe dietary supplements and herbal medicines are good for them.

At least one NIH study suggests that about 18% of adults in the U.S. take some form of “natural product,” that is an herb or remedy that is not a vitamin of mineral. These consist mostly of herbal remedies, with Echinacea, Gingko biloba, garlic, glucosamine, St. John’s Wort, Ginseng, and fish oil being among the most popular. However, there is growing research evidence that these popular products don’t have the health benefits for which most people take them.

Echineacea does not appear to have consistently demonstrable benefits for cold and flu sufferers (1, 2), and there is even less evidence to support other purported benefits (3). The strongest evidence of benefit for Gingko biloba initially was for Alzheimer’s and dementia (4), however two large, long-term clinical trials have failed to support this hoped-for effect (5, 6). I’ve already written repeatedly about the consistent failure of glucosamine to perform better than placebo, and about the equivocal findings for garlic. Ginseng doesn’t perform much better, with mixed results in generally small and not high-quality research studies. (7)

Among the strongest cases for herbal or other “natural” supplements are those made for St. John’s Wort and fish oil. St. John’s Wort does appear to have some benefit for mild depression, though no greater and with no fewer risks than conventional pharmaceuticals, which aren’t themselves always consistently better than placebo (8). Not exactly a ringing endorsement for one of the most intensively studies herbal remedies, to say that it works about as well as the lousy conventional therapies it is meant to replace or complement.

The evidence is better for fish oils, which have shown some consistent, repeatable benefits in clinical studies (9). However, additional recent work has called into question even this widely accepted conclusion (10). I myself have taken fish oil supplements for years, though I have recently decided to skip the capsules and just eat more fish since, as seems to be turning out to be true most of the time, the health benefits associated with eating particular foods don’t necessarily translate into benefits from supplements based on those foods. (For what it’s worth, I also took glucosamine for a while, with no obvious effects, until the evidence against a real benefit became strong enough to convince me I was wasting my money. The key to an evidence-based approach to healthcare is both being open to new ideas and willing to abandon ideas that fail to live up to their early promise). 

So while there is support for using some popular herbal remedies and other supplements, generally the evidence is far weaker than most people suppose. And the Decline Effect is readily apparent in the research on such remedies, with pre-clinical evidence and small, low-quality early trials showing apparent benefit which then gets progressively smaller and often disappears entirely and the amount and quality of the research grows. Promising ideas are worth investigating, but most fail to live up to their promise, so jumping on a new supplement bandwagon early is usually a mistake.

Vitamin and mineral supplements are the other major piece of the supplement market. Unquestionably, there is a real benefit for these in preventing specific nutritional deficiencies. However, the optimal intake of most vitamins and minerals for most individuals isn’t known. Age, sex, lifestyle, health, and many other variables affect how much of what we need to be as healthy as possible, and almost all recommendations to take more of these products than needed to prevent a deficiency are simply made up. General and irrational use of vitamin and mineral supplements not based on specific scientific evidence has consistently proved not only to not be beneficial but in some cases to be actively harmful (11, 12, 13, 14, 15, 16).

Of course, it is a given that people will continue to take supplements even based on flimsy evidence or even when the evidence is clear that benefits are lacking and there is real risk. The desire to control our health through therapeutic rituals, to believe what we wish were true even if it may not be, and the cognitive dissonance involved in letting go of deeply held beliefs when there is strong evidence against them are all factors that make it hard to give up behaviors that we feel, even mistakenly, are beneficial for us. So what should doctors do about our patients’ supplement use?

There is a lack of consistent and coherent policies among regulators and healthcare institutions to help doctors and patients manage the use of supplements concurrently with conventional medical therapies. Many patients (or veterinary clients) don’t tell their doctors about supplement use. Given that these products can interact in dangerous ways with conventional medicines, this present a real risk. So there are a number of things doctors should do, regardless of how favorably or skeptically they view herbal remedies and supplements, to minimize the risks to their patients associated with these products. 

1. Know What Your Patient is Taking

Doctors should ask their patients or clients about supplement use at every visit. I always ask my clients if their pets are on any medications. If they say “No,” I then ask about vitamins, supplements, herbal remedies, or other healthcare products, and they very often then reveal a whole host of things they are giving their pet.

Despite their belief that these products treat or prevent disease in their pets, these owners don’t think of the products as medicine since that word is generally associated with pharmaceutical products. Only specific and detailed questioning is likely to yield a true picture of what chemicals an owner is putting into their pet’s body. 

2. Understand the Evidence

We cannot counsel our clients effectively without being knowledgeable about the products they are interested in using. If a supplement or herbal remedy is truly beneficial, we should know this and know how to use it to help our patients. And if such a product presents a danger to our patients, or is simply a waste of our clients’ money, we should know that as well.

Obviously, I am skeptical about the value of many supplements. But I own quite a few references and textbooks about such products which I consult regularly, I maintain a subscription to the Natural Medicines Comprehensive Database, and I make the effort to be informed about the current scientific evidence regarding herbs and supplements (and to make that information available to others through this blog when I can). This seems a crucial part of being a truly useful resource for my clients and patients, even if often I end up having to tell that that the evidence is inconclusive and what they are giving their pets may or may not be in their best interests.

This is not to say that all veterinarians or veterinary students should undergo specialized training in herbal medicine or the use of supplements. All too often, such training is produced by individuals with firm beliefs about the value of such products who recommend them on the basis of historical use, personal experience, or kinds of evidence weaker than, and often in conflict with, the evidence of scientific research. To have an educated, informed, and science-based understanding of supplements does not require one to be trained in their use by practitioners already committed to their worth any more than being an educated, informed, and science-based critic of astrology or homeopathy requires one to train as an astrologer or homeopath.

3. Communicate Effectively

I see educating and informing my clients as a crucial part of my job. I cannot care for my patients effectively if I cannot communicate effectively with their owners. This means presenting the facts as I understand them, and my informed opinions (which, after all, is what the client is paying me for), clearly and in a way my clients can understand. This also means not taking an adversarial position against the values and beliefs my clients hold. I see it as an ethical duty to tell my clients when I believe they are treating their pets in a way that is useless or harmful, but this message cannot be heard unless it originates from a position of respect for their intentions and their feelings and a shared desire to do what is best for the animal.

My critics would likely be surprised at how many of my clients, with whom I have long-standing relationships of trust and cooperation, utilize therapies that I actively recommend they not use. Disagreement need not lead to personal antipathy, and my clients understand that even when I tell them something they don’t believe or don’t want to hear, I am not challenging their commitment to their pets’ wellbeing or their own competence as an owner.

Veterinarians need to be honest and explicit with their clients about the evidence concerning the therapies we offer and those we recommend against, and we need to not only share what we know but also admit what we do not know. When it comes to counseling clients about the use of supplements, making clear the uncertainty about these products, and that this uncertainty applies to their safety as much as to their purported benefits, is a necessary part of helping our clients make rational, informed decisions about their pets’ care. The biggest problem with the promotion and advertising of such supplements is that they make confident claims well beyond anything even remotely justified by real evidence.

Bottom Line

Overall, there is some reason to hope that some herbal remedies and nutritional supplements will one day be a useful tool in treating our patients. However, even the best-studied of such remedies currently have only weak evidence to support safety and efficacy, and most have nearly nothing but wishful thinking to justify their widespread use, especially in veterinary medicine where good quality clinical trials of such products are almost non-existent.

This means that we need to be aware of the evidence that does exist and explicit with our clients about what it does and does not tell us. And we need to be vigilant in watching out for harm from products that are often mistakenly assumed to be inherently safe. Clearly, such products will continue to be in fairly widespread use until the political climate changes to allow meaningful regulation of them and requirements that they be validated through proper, rigorous scientific study. Until then, veterinarians need to make the effort to be a source of reliable and honest information for our clients in order to protect and care for our patients.

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