FAQ: Nutrients

Pet Supplements

Pet Supplements

Pet owners are increasingly interested in supplements as part of a comprehensive approach to supporting their pets’ health and wellness. With an expanding marketplace and variable product quality, questions often arise about whether a supplement is appropriate and how to evaluate available options. 

The Purina Institute is committed to advancing pet care through evidence-based nutrition science. This FAQ page brings together insights from our library of trusted resources to help veterinarians and veterinary teams address client questions and support informed decision-making about pet supplements.

TABLE OF CONTENTS

Supplement Basics

What are supplements?

Supplements are broadly defined as “non-main meal products” and are intended to be fed as an addition to the pet’s main meal. While relevant in North America, the term “supplement” is not defined within the European Union or United Kingdom pet food (feed) regulations. Such products are regulated and covered under the term “complementary pet food,” which is defined as pet food that is not complete and balanced.1

Do all dogs and cats routinely need a supplement?

Healthy dogs and cats that eat a complete and balanced commercial pet food appropriate for their life stage do not need a supplement to meet their nutritional requirements. These pets typically receive 100% of their daily nutrient requirements from their food. However, owners of pets fed homemade diets should consult with a board-certified veterinary nutritionist for supplement guidance.

Individual dogs and cats may benefit from essential fatty acids, fiber, vitamins, or minerals in addition to what is present in their food or from functional ingredients not found in their food. In these cases, one or more supplements can be used to provide more personalized nutrition.

What supplements are commonly used in veterinary medicine?

Supplements commonly used in veterinary medicine include:

  • Glucosamine and chondroitin sulfate
  • Fish oil or omega-3 fatty acids
  • Omega-6 fatty acids
  • Fiber
  • Amino acids or their derivatives (e.g., taurine, S-adenosyl-methionine [SAMe])
  • Prebiotics, probiotics, or postbiotics
  • Zinc
  • Vitamins (e.g., B12 [cobalamin], E)

Pets at risk for or exhibiting signs of certain health conditions may benefit from these supplements.

For more information about supplements used in veterinary medicine, visit Supplements for Dogs and Cats

How are pet supplements regulated?

Supplement regulations vary worldwide. Veterinarians should understand their local regulatory environment. In general, disease claims are not permitted.1–3

Only approved or listed pet food ingredients are permitted in Europe and must follow pet food regulations. Medicinal claims cannot be made.

Supplements are generally regulated under the pet food category in Asia if no medicinal claims are made and nutritional composition is provided on the label.

In Latin America, pet supplements are also regulated.

In Australia, supplements are defined as “excluded nutritional or digestive” (END) products. They are normally not required to be registered with Australian Pesticides and Veterinary Medicines Authority (APVMA) unless they make claims about preventing, curing, or treating a disease.

In the U.S., the National Animal Supplements Council (NASC) provides labeling guidance, developed in discussion with the FDA and AAFCO, on supplement products for companion animals. To use the NASC “quality seal” on packaging, NASC member supplement manufacturers must comply with strict guidelines for quality assurance, adverse event reporting, and labeling standards.

Canada is currently the only country with a specific regulation for pet supplements—the Veterinary Health Products (VHP) Regulation. All ingredients must be found within the VHP permitted substance list; all supplements must be registered.

 

References

How to Choose a Pet Supplement

What should be considered when recommending a supplement?

Safety, efficacy, and quality should be the primary criteria for selecting a dietary supplement. However, finding reliable data can be challenging.1 Many products marketed as veterinary dietary supplements often lack quality control, safety, and clinical efficacy data.2

Quality may differ among manufacturers, thus recommending a supplement from a trusted company with experience in companion animal nutrition and a known reputation of quality and safety is essential. Ingredient purity, which can vary among suppliers, and the supplement manufacturing process may influence ingredient digestion and absorption and thus a supplement’s overall effects.

Since toxicity or side effects are possible with excessive levels of some nutrients, including some vitamins and minerals, over-supplementation should be avoided. All sources of a nutrient, including those in a complete and balanced diet, should be considered.3 

As supplements intended for humans may contain artificial sweeteners (e.g., xylitol) or other unsuitable ingredients, pet supplements are generally the best option. Formulated to appeal to pets, typically as palatable powders or chewable tablets, their administration can be easier—important as many supplements are administered long term and/or to animals that have disease conditions that may affect appetite.

When using a supplement to support a specific body system, it is prudent to seek out a supplement, if available, with scientific support4–13 in that area in the target species.

For more information about supplements for pets, including indications for use and how to choose them, watch the video Supplements for Pets: A Guide for Veterinarians, featuring Dr. Michael R. Lappin.

 

References

Probiotics & How to Choose One

What is a probiotic?

Probiotics are live, beneficial microorganisms (or bacteria) that when consumed in adequate amounts, can provide health benefits to the pet.1 Hundreds of bacterial species can be found in the gut; some are “good” (e.g., lactobacillus and bifidobacteria) and some potentially pathogenic (disease causing, e.g., clostridia). Collectively the bacteria that colonize the intestinal tract are known as the microbiota.2 The objective is to have an optimal balance between the good and the bad bacteria to help minimize the risk of digestive upsets.

Why would my pet need probiotics?

The intestinal tract—or gut—is home to trillions of bacteria that can have a huge impact on overall pet health.3 An imbalance in bacterial populations can affect the body’s immune system, lead to digestive disorders, inflammation of the intestines or diarrhea.4,5 The gut microbiota can even affect brain development and behavior.6 Probiotics are live bacteria that can help to shift gut microbiota toward more beneficial bacterial species, helping maintain an optimal balance.

How do probiotics work?

The most important immune-related function of the “good” bacteria is to protect from infection by harmful bacteria.7 The beneficial bacteria in probiotics prevent potentially pathogenic bacteria from flourishing by competing for space, secreting antibacterial substances, nourishing gut cells, and creating a more acidic environment that is unfavorable for pathogens.4 Maintaining an optimal balance of “good” and “bad” bacteria also improves fecal quality and can reduce flatulence.7 Beyond the gut, probiotics can also have positive impacts on behavior, helping anxious dogs maintain calm behavior.8

How are probiotics given to pets?

Probiotics can be provided as a dietary supplement or in pet food. Regardless of how the probiotic is administered, the probiotic strain (or strains) should be chosen based on the desired effect and the evidence of the probiotic’s efficacy in the target species.

Unfortunately, of the numerous probiotic products available for use, many do not contain the particular strains or quantity of colony-forming units (CFU) stated on the label. A CFU represents one bacterial cell and is the unit of measurement used to estimate the number of live, viable bacteria in a product. A 2011 study at the University of Guelph evaluated the labels and bacterial contents of 25 veterinary probiotic products and found only two of the 25 products delivered what the label described, highlighting the importance of choosing a reliable product.9

How do I know if a probiotic is good?

Probiotics are extremely strain-specific, and different strains within the same species can have very different health effects. Probiotics are also dose-dependent, therefore, clinical research is needed to establish the correct required amount of a particular strain of bacteria.

To be effective, studies should demonstrate that a particular probiotic:

  • Remains live and viable until the time of consumption
  • Is resistant to digestion by the stomach acids and intestinal enzymes
  • Reduces or prevents the adherence of pathogenic bacteria in the gut
  • Produce products that are unfavorable to the growth of “bad” bacteria
  • Promotes normal and balanced bacterial populations in the gut
  • Is safe for the pet
  • Enhances the overall health of the pet10

Is it better to have more bacteria, or more strains of bacteria?

Probiotic effectiveness is very strain-specific and dose-dependent. Different strains within the same species of bacteria can provide very different health effects, so blending them may not always be complementary and careful research needs to be done to ensure they do not work against each other.11,12 It is also important to consider that more CFU on the label of a product may not mean it is more effective, unless there is research showing the benefits of using a higher dosage. It is key that a product deliver the right dosage of a single, or blend of, probiotic proven by research to be effective for specific health concerns (i.e. diarrhea, general GI upset, anxiety, etc.).13

For an in-depth review of the gut microbiome, probiotics, and influencing pet health with probiotics, check out the monograph Understanding Probiotics and Their Impact on Pet Health.

 

References

References

Supplement Basics 

  1. FEDIAF The European Pet Food Industry. (2021, October). Nutritional guidelines for complete and complementary pet food for dogs and cats. https://europeanpetfood.org/wp-content/uploads/2022/03/Updated-Nutritional Guidelines.pdf
  2. Association of American Feed Control Officials. (2025). Supplements. Retrieved April 27, 2026, from https://www.aafco.org/consumers/understanding-pet-food/supplements/
  3. Association of American Feed Control Officials. (2025). Definition of food & drugs. Retrieved April 28, 2026, from https://www.aafco.org/resources/startups/definition-of-food-drugs/

How to Choose a Pet Supplement

  1. Hervera, M. (2025). Using supplements in small animal practice. In C. Lenox, J. Stockman, & C. Villaverde (Eds.), Purina Institute handbook of canine and feline well-pet nutrition (pp. 264–268). Embark Consulting Group, LLC.
  2. Elrod, S. M., & Hofmeister, E. H. (2019). Veterinarians‘ attitudes towards use of nutraceuticals. Canadian Journal of Veterinary Research, 83(4), 291–297.
  3. Association of American Feed Control Officials. (2025). Supplements. Retrieved April 27, 2026, from https://www.aafco.org/consumers/understanding-pet-food/supplements/
  4. Moreau, M., Troncy, E., del Castillo, J. R. E., Bedard, C., Gauvin, D., & Lussier, B. (2012). Effects of feeding a high omega-3 fatty acids diet in dogs with naturally occurring OA. Journal of Animal Physiology & Animal Nutrition, 97(5), 830–837. doi: 10.1111.j.1439-0396.2012.01325.x
  5. Mueller, R. S., Fieseler, K. V., Fettman, M. J., Zabel, S., Rosychuk, R. A. W., Ogilvie, G. K., & Greenwalt, T. L. (2004). Effect of omega-3 fatty acids on canine atopic dermatitis. Journal of Small Animal Practice, 45(6), 293–297.
  6. Hielm-Bjӧrkman, A., Tulamo, R.-M., Salonen, H., & Raekallio, M. (2009). Evaluating complementary therapies for canine osteoarthritis part 1: Green lipped mussel (Perna canaliculus). Evidence-Based Complementary and Alternative Medicine, 6(3), 365–373. doi: 10.1093/ecam/nem136
  7. McCarthy, G., O’Donovan, J., Jones, B., McAllister, H., Seed, M., & Mooney, C. (2007). Randomised double blind, positive-controlled trial to assess the efficacy of glucosamine/chondroitin sulfate for the treatment of dogs with osteoarthritis. The Veterinary Journal, 174(1), 54–61.
  8. Ruff, K. J., Kopp, K. J., Von Behrens, P., Lux, M., Mahn, M., & Back, M. (2016). Effectiveness of NEM® brand eggshell membrane in the treatment of suboptimal joint function in dogs: A multicenter, randomized, double-blind, placebo-controlled study. Veterinary Medicine: Research and Reports, 7, 113–121.
  9. Van den Abbeele, P., Duysburgh, C., Rakebrandt, M., & Marzorati, M. (2020). Dried yeast cell walls high in beta-glucan and mannan-oligosaccharides positively affect microbial composition and activity in the canine gastrointestinal tract in vitro. Journal of Animal Science, 98(6), skaa173. doi: 10.1093/jas/skaa173
  10. Fries-Craft, K., Kilburn-Kappeler, L. R., Aldrich, C. G., & Bobeck, E. A. (2023). Dietary yeast beta 1,3/1,6 glucan supplemented to adult Labrador Retrievers alters peripheral blood immune cell responses to vaccination challenge without affecting protective immunity. Journal of Animal Science, 101, skad029. doi: 10.1093/jas/skad029
  11. Bybee, S. N., Scorza, A. V., & Lappin, M. R. (2011). Effect of the probiotic Enterococcus faecium SF68 on presence of diarrhea in cats and dogs housed in an animal shelter. Journal of Veterinary Internal Medicine, 25(4), 856–860. doi: 10.1111/j.1939-1676.2011.0738.x
  12. Benyacoub, J., Czarnecki-Maulden, G. L., Cavadini, C., Sauthier, T., Anderson, R. E., Schiffrin, E. J., & von der Weid, T. (2003). Supplementation of food with Enterococcus faecium (SF68) stimulates immune functions in young dogs. The Journal of Nutrition, 133(4), 1158-1162. doi: 10.1093/jn/133.4.1158
  13. Webb, C., & Twedt, D. (2008). Oxidative stress and liver disease. Veterinary Clinics of North America: Small Animal Practice, 38(1), 125–135. doi: 10.1016/j.cvsm.2007.10.001

Probiotics & How to Choose One

  1. Case, L. P., Daristotle, L., Hayek, M. G., & Raasch, M. F. (2011). Canine and feline nutrition: A resource for companion animal professionals (3rd ed.). Mosby.
  2. Pinna, C., & Biagi, G. (2014). The utilization of prebiotics and synbiotics in dogs. Italian Journal of Animal Science, 13, 3107. doi: 10.4081/ijas.2014.3107
  3. Sender, R., Fuchs, S., & Milo R. (2016). Revised estimates for number of human and bacteria cells in the body. PLoS Biology, 14(8), e1002533. doi:10.1371//journal.pbio.1002533
  4. Kelly, M. The role of probiotics in GI tract health. Nestlé Purina Petcare, Purina ProPlan Veterinary Diets.
  5. Ng, S. C., Hart, A. L., Kamm, M. A., Stagg, A. J., & Knight, S. C. (2009). Mechanisms of action of probiotics: Recent advances. Inflammatory Bowel Diseases, 15, 300–310. doi: 10.1002/ibd.20602
  6. Wiley, N. C., Dinan, T. G., Ross, R. P., Stanton, C., Clarke, G., & Cryan, J. F. (2017). The microbiota-gut-brain axis as a key regulator of neural function and the stress response: Implications for human and animal health. Journal of Animal Science, 95, 3225–3246.
  7. Czarnecki-Maulden, G. L., Kelly, M. R., & Cline, J. L. (n.d.). The –otics: pre and probiotics… What are they? Are they useful in your practice? Nestlé Purina PetCare.
  8. McGowen, R. T. S. (2016, March 31–April 2). Oiling the brain or cultivating the gut: Impact of diet on anxious behavior in dogs. Pet Nutrition: Beyond Essential, Nestlé Purina Companion Animal Nutrition Summit, Fort Lauderdale, FL, USA.
  9. Weese, J. S., & Martin, H. (2011). Assessment of commercial probiotic bacterial contents and label accuracy. The Canadian Veterinary Journal = La revue veterinaire canadienne, 52, 43–46.
  10. Rolfe, R. D. (2000). The role of probiotic cultures in the control of gastrointestinal health. Proceedings of the Probiotic Bacteria: Implications of Human Health Symposium. Journal of Nutrition, 130, 396S–402S. doi: 10.1093/jn/130.2.396S
  11. Kekkonen, R. A., Kajasto, E., Miettinen, M., Veckman, V., Korpela, R., & Julkunen, I. (2008). Probiotic Leuconostoc mesenteroides ssp. cremoris and Streptococcus thermophilus induce IL12 and IFN-γ production. World Journal of Gastroenterology, 14, 1192–1203.
  12. Viljanen, M., Kuitunen, M., Haahtela, T., Juntunen-Backman, K., Korpela, R., & Savilhati, E. (2005). Probiotic effects on faecal inflammatory markers and on faecal IgA in food allergic atopic eczema/dermatitis syndrome infants. Pediatric Allergy and Immunology, 16, 65–71.
  13. Sanders, M. E. (2008). Probiotics: Definition, sources, selection, and uses. Clinical Infectious Diseases, 46, S58–S61. doi: 10.1086/523341