Do Pet Supplements Really Work?

I became aware of this dimension of the supplement market thanks to a phone call from an old friend. She was in Costco, tunneling her way through the towering aisle of pet products, when she saw a dietary supplement that claimed that it could treat arthritis in dogs. “Does it work?” she asked me. Her dog was over ten years old, and he was moving slowly. Of course, she wanted to take the best possible care of him. However, the supplement, even in bulk, was expensive. Would it work? Was it entirely safe? I told her: “I don’t know if it will help, but I can try to find out.”

I understood her situation and was sympathetic: I once had a beautiful Italian greyhound named Bisou. My son grew up with her, we all adored her, and we bent over backwards to get her anything she needed. She truly was part of the family.


Thus far, we have learned that most American adults take a dietary supplement daily, and that supplement consumption is on the rise for many age groups, including the elderly, young adults, and children. But the trend does not stop there. Increasingly, people are buying supplements and giving them to their pets as well.

To be honest, when I spoke with my friend, I didn’t know what an interesting world I was promising to investigate. First, I found that, despite the economic recession of the late 2000s, pet ownership is higher now than in the 1990s: In 2017, 68% of American households owned a pet—up from 56% in 1998 (American Pet Products Association, 2017). Taking care of all those pets comes with a sizable price tag: $69 billion was spent on the purchase and maintenance of pets in 2017, with the number one spending category being food (American Pet Products Association, 2017). Pet dietary supplements are also becoming a common expenditure. Currently, “a third of all U.S. households with dogs use supplements, as do about a fifth of households with cats” (Burns, 2017).

Not only do more households have pets, but those that do tend to see their pets differently than they would have fifty years ago. Pets are now an integral part of the family, and market researchers emphasize the dawn of the “fur baby” and “pet parents” (Olivo, 2017). From a business perspective, this inspires endless opportunities to make a profit helping people care for and enjoy the pets that they are so very attached to. Just as people worry about their own health, they are also concerned about their pets’ health, which has led to a lucrative market for specialty “health” foods and supplemented treats.

If you live in an urban area, you have probably witnessed some manifestation of these pet-specialty boutiques and products firsthand. Especially in the more affluent parts of the country, pet owners like to extend versions of their own favorite luxuries to their animals. Here in Orange County, there are pet bakeries, such as “Top Dog Barkery,” in Newport Beach, famous for making personalized birthday cakes for pooches and throwing “Pup Showers” when someone’s furry friend is expecting. Bacon and peanut butter usually feature heavily in their offerings. (Not aware that the “Top Dog Barkery” was dedicated to pet treats, the first time I passed by it, I walked in and bought a small, tasty-looking chocolate cookie—and ate it myself. It smelled and tasted like dried chicken. Who knows what the employees must have thought!)

All across the country, the pet luxury business is booming as never before. In New York City, you can book a $200-a-night pet hotel suite that features full-sized beds and “dog-friendly programming” (Rogers, 2017). What that might be, I can only imagine. People might see this as an expression of a deep love for animals that is heartwarming, or the more skeptical may find such expenditures frivolous. Either way, if your cat has a Tiffany & Co. collar or you buy Fido some “Doggles” (specially designed dog sunglasses), there is no harm done to the animal. But that is not true when it comes to purchases that affect the diet of pets. Here, just as with human supplements, even though the word “healthy” might be plastered all over the product, there may be no hard, scientific evidence that it is going to create a better quality of life for your pet.


One glance at the pet food aisle reveals that health-based marketing is everywhere: exotic “superfood” ingredients (ostrich or açaí, anyone?) and “clean” non-GMO diets for pets are becoming more and more mainstream. Pet foods and supplemented products seem to be engaged in a fierce competition to prove that they are “healthier” than all the rest. This is good marketing because people are willing to spend a lot to buy what they think will give their animals optimum nutrition. A research team in London found that “nearly eight out of 10 pet owners said the quality of their pets’ food is as important as their own” (Olivo, 2017). Another study from the Journal of Psychology and Marketing found that many dog owners are actually more serious about the healthiness of their pets’ food than they are about what they put on their own plates: while 64.1% of dog owners rated their level of attention to their own diet as “serious” to “very serious,” 78.4% said this about their pets’ food (Tesfom & Birch, 2010).

Companies are responding by creating luxury pet food aimed at these concerned owners. A friend of mine, while at a dinner party, recently caught her toddler chowing down on doggy treats and instinctively panicked: “Icky! Icky!” she cried, while rushing to snatch the bag away from him. But then she examined the ingredient label: organic blueberries, organic seaweed, organic whole-wheat flour, and a smidge of organic cane sugar. She realized that the dog treats were healthier (and more expensive) than her kid’s fruit snacks.

On the one hand, consumer preferences have encouraged the pet food market to invest in an admirable increase in the quality and transparency of some pet food. This is great news for everyone. But another consequence of consumer enthusiasm for healthier pets is vulnerability to predatory health-based marketing tactics. Products without any sound scientific research behind them may hide behind unwarranted claims to improve health and wellness. In some cases, companies even perpetuate health myths in order to sell their unproven products.

What kinds of potentially dangerous “health” fads do we find in pet nutrition? Some of them mimic human health trends: “Raw” diets, for instance, echo the logic of “paleo” diets for human beings. The general marketing story that we are told is that by eating a “natural” diet closer to that of our distant ancestors, we can reach a more perfect balance of health and harmony. For dogs and cats, this means returning to raw, meat-based diets.

But do such diets necessarily lead to better health? A recent study in the Netherlands that focused on 35 commercially sold raw dog food brands found a very high risk of these products containing harmful bacteria: 80% of the products contained E. coli; 50% were found to have species of Listeria; and 20% were contaminated with Salmonella. Two of the products had Toxoplasma gondii, a parasite that can infect cats and spread to people, with particular risk to pregnant women and babies. The authors suggest that the problem is severe enough to warrant special warning labels for raw pet diets (van Bree et al., 2018).

Another pet diet trend that mimics human health trends is vegetarianism for dogs. Some vegetarian dog owners have wanted their animals to also adopt a vegetarian diet. For cats to survive, they must eat meat because it contains essential nutrients for them, but, in theory, dogs can receive all their nutrition from plants. But are vegetarian diets best for dogs?

Of course, this in part depends on the exact content of a specific vegetarian diet, but the general 

answer is that these diets meet the nutritional needs of canines less often than conventional dog diets do. A study published in the Journal of the American Veterinary Medical Association evaluated vegetarian diets formulated for dogs to determine protein and amino acid concentrations and assess labeling adequacy. The researchers reported that of the twenty-four foods tested, most were not compliant with the minimum labeling standards of the Association of American Feed Control Officials Dog and Cat Food Nutrient Profiles and were nutritionally inadequate (Kanakubo et al., 2015).

Similarly, in an interview with The New York Times, Dr. Lisa Freeman, professor at Cummings School of Veterinary Medicine at Tufts University and a board-certified veterinary nutritionist, stated, “There were no long-term studies on the effects of vegetarian diets in dogs and just because veganism has health benefits in humans, it does not mean it is a healthier diet for dogs” (McDermott, 2017).

There is a strong incentive for pet companies to design and market their products toward human health trends. It’s easy to piggyback their products on the already successful marketing campaigns in the world of human food and supplement sales.

So, for example, while gluten-free items for humans have stormed their way onto menus and store shelves, they are also becoming a key offering in pet food. There is “a strong rise in gluten-free and grain-free formulations for both dog and cat foods,” according to Lu Ann Williams, a researcher with Innova Market Insights. “Overall, over one-fifth of [pet product] launches carried a gluten-free positioning, rising to nearly a quarter for dog food” (Burns, 2017). This change is taking place not because science has found that a quarter of all dogs suffer from gluten allergies, but simply because human health trends, driven in part by people’s choices and in part by the encouragement of marketing campaigns, have spilled over onto pet products. While some people with severe allergy to gluten (celiac disease) should attempt to avoid any exposure to substances containing gluten, as long as they are not inadvertently ingesting gluten- containing products, they are not at risk.

In summer of 2018, the FDA’s Center for Veterinary Medicine opened an investigation into multiple reports of canine dilated cardiomyopathy (DCM)—an enlargement of the heart that can lead to heart failure. Oddly, they found this problem occurring in breeds not usually genetically predisposed to it. The initial findings suggest that the common thread in these cases of DCM may be grain- free diets: “In each of the cases the dogs were being fed certain pet foods that listed potatoes, or multiple legumes such as peas, lentils, other ‘pulses’ (seeds of legumes), and their protein, starch and fiber derivatives as main ingredients.” In other words, most were being fed diets labeled as “grain-free.” The report concludes, “It is not yet known how these ingredients are linked to cases of DCM,” but it still warns consumers to exercise caution (National Animal Supplement Council, 2018).

The New York Times followed the investigation, interviewed the stunned owners of the afflicted animals, and noted, “The possibility that expensive food, lovingly chosen, could make one’s adored pet devastatingly ill is sending shudders through dog owners.” One woman who had been feeding her golden retriever a grain-free diet for years before he developed DCM said that she had looked at the ingredients and thought: “It looked like something I would eat, so I thought it would be all right” (Hoffman, 2018).

Though the exact link between DCM and diet has not yet been uncovered, the collective angst of these dog owners can still serve to remind us of an important lesson: It is always possible that a product perceived as “healthier” is actually harmful when it does not match the real nutritional needs of a specific person (or, in this case, canine). Advertising often implies what it cannot prove, and it then generalizes when a specific assessment is called for. Dr. Freeman states that, because of the many “myths and misperceptions” surrounding pet food, it is all too easy for consumers to unknowingly “take a step in the wrong direction when the marketing outpaces the science” (Freeman, 2018).

The marketing of fortified pet foods and supplements closely resembles that of dietary supplements for humans. The same descriptors show up again and again: “natural,” “clean,” and “non-GMO” are favorites. Similar claims and assumptions are also made about what it takes to be well. Marketing campaigns position themselves not as salespeople but as “educators” who need to teach pet owners about their product’s benefits, using language that sounds scientific and clinical but also emphasizes the supposed safety of relying on wholly “natural” cures. Sometimes the most effective sales tools seem at first to be an educational resource or website, but in truth they are sales platforms that exist for the purpose of pointing consumers to a particular product.

Dr. Freeman writes, “The pet food industry is a competitive one, with more and more companies joining the market every year. Marketing is a powerful tool for selling pet foods and has initiated and expanded fads.” The prowess of marketers and the health-positioning of their product makes it difficult for pet owners to know what the best food for their pet truly is (as opposed to the one with the loudest or most attractive marketing). “Because of the thousands of diet choices, the creative and persuasive advertising, and the vocal opinions on the internet, pet owners aren’t able to know if the diets they’re feeding [their pets] have nutritional deficiencies or toxicities” (Freeman, 2018).

Let the buyer beware: avoid fads and be the skeptic. Most of the time, simply taking a walk is better for us than trying out the newest health trend. And that goes for dogs, too.


So what about pet supplements specifically? So far, this article has dealt with the big picture of popular attitudes toward pet health and the pet industry’s response in its product manufacturing and marketing. But what about my friend’s question: Could a supplement be used to help an animal with aging issues or pain, or to combat a specific condition, such as arthritis?

If we looked only at the sales numbers for pet supplements, we would be tempted to say “yes.” According to a report by Packaged Facts, “…factors related to COVID-19 caused sales of pet supplements to shoot up 21% in 2020 to nearly $800 million, quadrupling the rate of sales growth seen in 2019” (Packaged Facts, 2021). The most popular pet supplements are multivitamins, and the most popular condition-specific supplements are those that claim to promote joint or heart health, and to maintain coat and skin, followed by those that support the digestive tract (Burns, 2017). It is estimated that the sales of pet dietary supplements will exceed $1 billion by 2025 (Packaged Facts, 2021). For so many people to spend so much money, these products must have some efficacy, right?


Unfortunately, there are few well-designed clinical trials on pet supplements to back up all these sales. Without knowing exactly what effect a supplement will have on the animal taking it, and what dosages are appropriate, the use of such supplements is inherently risky.

How can we sort through all the advertising and assess the usefulness of individual pet supplements? Organizations like the American Veterinary Medical Association are a good place to look for the latest developments in pet supplement science based on clinical trials involving the animals themselves.

What does science have to say, for instance, about one of the oldest and most common pet supplements, glucosamine?

Glucosamine, one of the components of cartilage, which cushions joints, has long been used to treat arthritis and joint pain. Though large human clinical trials have been conducted on glucosamine, the results were inconclusive and only mildly optimistic. This is one of the few areas in which many studies have also been conducted on dogs. But these trials were of varying quality, using different dosages, forms, and combinations of glucosamine products. Because the major objective is to alleviate pain, the results can also be difficult to quantify. All in all, researchers have not been able to show significant benefits (Bhathal et al., 2017).

In fact, in 2016, the American Veterinary Association issued a statement reversing its earlier endorsement of glucosamine. They claimed that it was not consistent with their “evidence-based” commitment. The science simply was not showing any convincing proof of its effectiveness. The good news is that these trials have shown that glucosamine in moderate doses is benign in its side effects. While not able to help much, it is unlikely to do much harm, either (Burns, 2017).

What about fish oil, which, after glucosamine, is the most common supplement added to a pet’s diet?

The results of individual clinical studies have shown some hopeful signs that fish oil may be an effective anti-inflammatory intervention for dogs, especially when used in conjunction with other treatments such as glucosamine (Olivry et al., 2010). Fish oil may also treat the symptoms of arthritis, though with very marginal benefit. In one study of seventy-seven dogs with osteoarthritis, half were given fish oil supplements and the other half were given corn oil. After sixteen weeks, there was overall “not a major statistically significant benefit” found in the fish-oil group. The research team did find, however, “a true but small relief in symptoms” on some measures for the dogs taking fish oil, and they encouraged further study (Hielm-Bjorkman et al., 2012). But other trials have shown that both dogs and cats who take fish oil supplements can also experience harmful side effects, such as altered platelet function, which can result in bleeding, weight gain, and slow wound healing (Tudor, 2013).

Though there is significant interest in pet supplements and “functional” pet foods that are fortified with vitamins, minerals, and herbs, pet owners’ concern about pet health is often better directed toward broader health practices. Under some circumstances, supplements may help an ill or malnourished pet, but for most pets on a standard scientifically formulated diet, deficiency is not the major health issue that they are facing: obesity is. In the United States, 56% of dogs are overweight or obese, as are 60% of cats (Association for Pet Obesity Prevention, 2018). Like people, the best way for overweight pets to become healthy and reduce stress on their bodies is not to take supplements, but to lose weight through exercise and portion control.


Who is keeping track of the pet products that Americans are buying, and ensuring their safety?

The FDA has regulatory powers over pet supplements, which almost always fall into the same legal category as all other types of pet food and are treated as “animal feed.” In addition, each state has its own standards and regulatory powers over animal feed determined by their Department of Agriculture.

Interestingly, the FDA and individual states take a backseat on creating regulatory guidelines. Instead, a private organization, the Association of American Feed Control Officials, establishes uniform labeling and quality standards for the industry, although it has no regulatory powers (Schlesinger & Day, 2017). Pet food companies themselves have always self-policed the industry to a certain extent, with the top producers forming trade associations that seek to standardize quality. In part, this is necessary because pet diets are so limited: Any pet diet must meet exactly all the nutritional requirements of the animals that they are intended for.

What many consumers do not know is that the FDA does not proactively monitor quality control for pet supplements on the front end. In practice, active FDA involvement will occur only after enough adverse effects have been reported, which may then force a recall of the product. This, as we know, is the same situation as for human dietary supplements. There is no mandated pre- market testing, and products are only investigated after enough reports are received of harm caused to consumers.

In 2007, for instance, the laissez-faire regulatory situation in the pet industry boiled over into one of the largest recalls in FDA history. A Chinese supplier of ingredients to multiple pet food manufacturers had tainted its wheat gluten with melamine to make it appear to have a higher protein level. Reports of kidney failure and pet death came from veterinarians and individuals across the country, and the frantic chase for an answer finally revealed the fraudulent supply chain. Over 5,000 different products were recalled under dozens of different labels and companies. The first company to suspect the problem, Menu Foods, alone, lost over $40 million dollars from the recall (FDA, 2018).


First, it is common sense to check your pet’s daily intake of nutrients before adding more nutrients to their diet. The American College of Veterinary Nutrition’s website assures owners that “if your pet is eating a complete and balanced commercially available pet food, supplements are not recommended unless specifically prescribed by your veterinarian” (American College of Veterinary Nutrition, 2016). Do not let pressure from health-oriented marketing campaigns overwhelm your common sense.

Second, look for independent auditing of the company and product. It doesn’t matter how chic, raw, expensive, professional, or homemade a supplement appears to be; the best way to know that it is not contaminated is to simply investigate each product. Check the FDA’s website for recalls. And if you see a problem with a pet supplement, be sure to report it to the FDA’s Consumer Complaints department through the portal available on their website (and listed below in the resource box).

Third, remember that supplements, including herbal remedies, may have adverse effects and/or interact with other medications or other supplements that your pet is taking (Lenox and Bauer, 2013). For example, if your pet is on any blood thinner medications, they should not take ginkgo biloba because the risk of bleeding increases. Excessive vitamin E can prevent blood from clotting around cuts and scratches, which can turn to profuse bleeding (Goodman & Trepanier, 2005). Though little testing has been done, it is likely that some supplements can decrease a pet’s ability to absorb medication, just as with human beings.

In every case, adding a supplement or turning to a specialty diet for your pet should only be done with the recommendation and under the supervision of a veterinarian. Marketing is not a substitute for training and medical expertise.

And finally, keep in mind that the Amended Dietary Supplement Health and Education Act (1994) distinguished pet supplements from food additives and placed supplements in the same category as food. It also allowed supplement manufacturers to market and sell pet supplements without review—meaning the FDA is barred from regulating them. This means that you need to do your own research on the safety (and efficacy) of your pet supplements.


American College of Veterinary Nutrition. (2016). Frequently asked questions. American College of Veterinary Medicine. asked-questions/

American Pet Products Association. (2017). Pet industry market size & ownership statistics. American Pet Products Association.

Association for Pet Obesity Prevention. (2018, April 19). 2017 pet obesity survey results: U.S. pet obesity steadily increases, owners and veterinarians share views on pet food. Association for Pet Obesity Prevention.

Bhathal, A., Spryszak, M., Louizos, C., & Frankel, G. (2017). Glucosamine and chondroitin use in canines for osteoarthritis: A review. Open Veterinary Journal, 7(1), 36–49. doi:

Burns, K. (2017, January 4). Assessing pet supplements. American Veterinary Medical Association (AMVA).

Food and Drug Administration. (2018, September 4). Melamine pet food recall

of 2007. Department of Health and Human Services, Food and Drug Administration.

Freeman, L.M. (2018, June 4). A broken heart: Risk of heart disease in boutique or grain-free diets and exotic ingredients. Cummings Veterinary Medical Center at Tufts University. heart-risk-of-heart-disease-in-boutique-or-grain-free-diets-and-exotic- ingredients/

Goodman, L., & Trepanier, L. (2005). Potential drug interactions with dietary supplements. Compendium on Continuing Education for the Practicing Veterinarian 27(10). Retrieved from: dietary-supplements                                                                 

Hielm-Bjorkman A., Anturaniemi (o.s. Roine), J., Elo, K., Lappalainen, A.K., Junnila, J.J.T., & Laitinen-Vapaavouri, O.M. (2012). An un-commissioned randomized, placebo-controlled double-blind study to test the effect of deep-sea fish oil as a pain reliever for dogs suffering from canine OA. BMC Veterinary Research, 8(1), 157.

Hoffman, J. (2018, July 24). Popular grain-free dog foods may be linked to heart disease. The New York Times. disease.html

Kanakubo, K., Fascetti, A.J., & Larsen, J.A. (2015). Assessment of protein and amino acid concentrations and labeling adequacy of commercial vegetarian diets formulated for dogs and cats. Journal of the American Veterinary Medical Association, 247(4), 385–392. doi:

Lenox, C.E., & Bauer, J.E. (2013). Potential adverse effects of omega-3 fatty acids in dogs and cats. Journal of Veterinary Internal Medicine/American College of Veterinary Internal Medicine, 27(2), 217–26. doi:

McDermott, M.T. (2017, June 6). The vegan dog. The New York Times.

National Animal Supplement Council. (2018, July 12). FDA investigates potential link between diet, dog heart disease. National Animal Supplement Council. dcm/

Olivo, L. (2017). Top quality nutrition for family pets. Nutraceuticals World. quality-nutrition-for-family-pets/.

Olivry, T., DeBoer, D.J., Favrot, C., Jackson, H.J., Mueller, R., Nuttall, T., & Prélaud, P. (2010). Treatment of canine atopic dermatitis: 2010 clinical practice guidelines from the international task force on canine atopic dermatitis. Veterinary Dermatology, 21(3), 233–48.                                                                   doi:

Packaged Facts. (2021, January 20). Pet supplements in the U.S., 8th ed. Packaged Facts.

Rogers, K. (2017, August 18). Pet hotels are riding the booming market for animal luxuries. CNBC: On the Money. market-for-animal-luxuries-.html

Schlesinger, J., & Day, A. (2017, May 6). What is really in the food your dog or cat is eating? CNBC: On the Money. cat-is-eating.html

Tesfom, G., and Birch, N.J. (2010). Do they buy for their dogs the way they buy

for themselves? Psychology and Marketing, 27(9), 898–912. doi:

Tudor, K. (2013, August 8). Fish oil: The dangers of too much. Pet MD. too-much-fish-oil-30731

van Bree, F.P.J., Bokken, G.C.A.M., Mineur, R., Franssen, F., Opsteegh, M., van der Giessen, J.W.B., Lipman, L.J.A., & Overgaauw, P.A.M. (2018). Zoonotic bacteria and parasites found in raw meat-based diets for cats and dogs. Veterinary Record, 182(2), 50. doi:

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