Pet supplements: Which ones are backed by science?

Pet supplements: Which ones are backed by science? - cat being fed supplement tablet

The pet supplement industry is massive and can be confusing to navigate for both pet owners and veterinarians. You may be surprised to learn most pets don’t need any supplements at all. Read on if you’ve ever wondered:

  • What are dietary supplements?
  • What supplements are available for pets?
  • Do supplements provide benefits for pets?
  • Should my pet take any supplements?

It’s important for pet owners to know which supplements are backed by scientific evidence and which can be downright harmful or dangerous for our pets. Prior to purchasing supplements, always discuss adding them to your pet’s diet with a veterinarian. Your vet will give you the information you need to determine if supplementation is necessary for your pet’s health and worth the cost.

What is a dietary supplement?

Dietary supplements are a treat, powder, tablet, or other digestible that is intended to support nutrition or therapy. They are not considered pet food or medication. Although supplements seem similar to over-the-counter and prescription medications, both pet and human supplements differ from these products because the way they are produced and packaged is not regulated. What this means is despite having marketing similar to medications, supplements do not require the U.S. Food and Drug Administration aka the FDA (or the regulating body of countries outside the USA) to observe safety, quality, or effectiveness before they are put on shelves for consumers. Supplements are popular among pet owners, but pets should never receive human supplements due to the risk of toxicity caused by ingredients or high doses.

What types of popular supplements are there for pets?

The dietary supplement industry is a $15 billion industry. Over half of Americans take human supplements, and this trend is beginning to increase in pets as well. Roughly one-third of U.S. dogs and one-fifth of U.S. cats take some kind of supplement. There are many popular types of supplements for pets on the market.

Joint health supplements

Joint support and health supplements are among the most popular condition-specific supplements given to pets. Ingredients vary, but glucosamine and chondroitin are two of the most common. There are a few studies that have shown glucosamine and chondroitin to benefit pets with osteoarthritis and ease their symptoms, but mixed results mean more studies are needed.

Fish oil and omega fatty acids

Omega fatty acids are found in fish and green leafy vegetables, and fish oil is usually the source of omega fatty acid supplements. Fish oil is often given to pets for dry skin, heart disease, kidney disease, and types of cancer. While fish and leafy green vegetables are widely considered healthy for pets, there is little evidence to support that fish oil supplements provide any benefits, especially for healthy pets. In addition, overharvesting of small fish to create fish oil supplements has negative environmental impacts on ocean ecosystems.

Stress relief and calming remedies

For stress relief and calming effects, L-Theanine is one of the most commonly used ingredients in supplements, but other ingredients, such as melatonin and tryptophan, can be included as well. Evidence supporting the effectiveness of behavioral supplements varies widely between ingredients and more research is needed to prove any benefit.


Probiotics are live microorganisms that affect the gut biome in humans and other mammals. Dogs have different gut flora than cats, so probiotics are different for each species. Probiotic supplements appear to be safe for use in most pets, but should be used with caution in immunocompromised patients. Probiotics and other gut health or digestive support supplements do not appear to be beneficial for healthy pets with balanced diets, but they can sometimes assist pets who have had their gut biome altered due to disease. Even then, probiotics must be species-specific as every animal’s natural biome is different.


Turmeric has been used for thousands of years for its anti-inflammatory properties. However, there has not been much research demonstrating any positive effects of turmeric on dogs and cats. There is some anecdotal evidence that turmeric helps with inflammation caused by arthritis and joint pain. In a small study, the use of turmeric helped treat paralysis from intervertebral disc disease in canine patients. However, this study did not list other medications or therapies the patients were receiving for their conditions. More studies are needed to understand the effects of turmeric supplements on pets.


Cannabidiol (CBD) is becoming increasingly popular for treating conditions in both humans and animals. It is sometimes used to treat pain and seizures. Some small studies have also shown CBD to help canine stress and anxiety. However, currently there are not many long-term studies on CBD’s medicinal benefits as it only recently became legal for many consumers to purchase. Public access to cannabis is expected to drive ongoing research into its medicinal value. Always use CBD under the guidance of a veterinarian and never give your pet a CBD product meant for people. Many human CBD products contain xylitol, THC, or highly concentrated synthetic cannabinoids.

Vitamin and mineral supplements

Vitamins and minerals, such as potassium, magnesium, and selenium are necessary for normal bodily function in dogs and cats. Healthy animals that receive balanced diets do not need additional vitamins or minerals. In some cases, too much of one of these minerals through supplements can cause toxicity.

Vitamin and mineral supplements do have some specific uses in veterinary medicine. Potassium supplements are often given to cats with kidney disease as the disease causes potassium deficiency. Selenium has been used experimentally in treatments for canine infertility.

Essential oils

Unlike the other supplements on this list, essential oils show no science-backed health benefits for dogs and cats. Many essential oils can be irritating or even toxic when touched, inhaled, or ingested by dogs and cats. Essential oils vary widely in concentrations and ingredients and are not regulated. For healthy pets, occasionally using an essential oil diffuser in a large space is likely not an issue, but may cause problems for birds or pets with respiratory issues.

Colloidal silver

Colloidal silver is a supplement made of tiny silver particles in a liquid suspension. Silver has some antimicrobial and antibacterial properties, but its use as a dietary supplement in humans or animals has little scientific backing. Colloidal silver can be toxic when ingested by pets. The FDA put out a warning in 1999 that colloidal silver is not safe or effective for treating any disease or condition. It’s best to stick with antibiotics prescribed by your veterinarian if your pet is sick.

Do nutritional supplements provide health benefits for pets?

Although some supplements show promise in scientific studies, most supplements you see in the local pet store do nothing to help your pet and may even be harmful.

What are the potential benefits of supplements?

Pet owners may assume that supplements actually contain what they say they do, and that’s not always the case. The supplement industry is not regulated by the FDA, so products vary widely in both their contents and the concentrations. This lack of quality control makes it difficult to determine if a particular supplement is beneficial or not.

Some supplements may benefit dogs and cats with certain health conditions. “Providing potassium to cats with kidney disease is a great example of a dietary supplement with proven benefits in a specific situation,” states Dr. Jo Myers, a Vetster veterinarian. Always consult a veterinarian about providing supplements to your pet. A vet can help you understand when supplements are actually necessary and learn which manufacturers have good quality control.

What are the potential adverse effects of supplements?

When taken in large amounts, some supplements may cause toxicity in pets. Others are poisonous or hazardous in any amount. Symptoms of supplement toxicity can vary depending on what was ingested and in what amount. Symptoms range from stomach upset to seizures.

Should pets take supplements?

Healthy pets with a well-balanced diet do not need additional diet supplementation to remain healthy. Pet supplements have not been proven to prevent any type of illness. A balanced diet has all the essential nutrients your pet needs and is the best way to support brain, skin, and heart health. Supplements are not a replacement for a balanced diet. Commercial animal food contains the right amount of vitamins and minerals needed for normal bodily function. If your pet develops a health condition that requires a dietary supplement, it is best to follow a veterinarian’s advice on brand, type, and dosage.

How do I choose a good supplement?

The supplement industry is massive and skilled at using advertising to convince pet parents to purchase their products. Pet supplements with the National Animal Supplementation Council (NASC) seal are considered quality products that are safe and effective due to increased regulation and testing for safety and effectiveness. Discuss your options with your veterinarian and look for a supplement with the NASC seal if you decide your pet does need some additional dietary support. If you have questions about dietary supplements for your pet or if your pet needs supplementation in their diet, you can have a discussion with a Vetster veterinarian in a virtual vet appointment.

FAQ - Pet supplements: Which ones are backed by science?

Are pet supplements worth it?

While some supplements have been shown to provide health benefits for pets with specific health conditions, healthy pets with balanced diets do not need extra supplementation. You will likely be wasting your money. Supplements are usually not harmful, but you may also be putting your pet at risk of exposure to potentially harmful ingredients.

Does my pet need supplements?

Healthy pets receiving a daily well-balanced diet receive adequate vitamins and minerals and do not need additional supplements. If your pet has a deficiency or other medical condition and would subsequently benefit from a supplement, it’s best to talk to a vet about the type, brand, and dosage before giving your pet new supplements.

Is fish oil good for pets?

There are limited studies that show fish oil or omega fatty acid supplements provide health benefits in pets. However, some fish oil may contain mercury that can cause toxicity, and overfishing for the creation of fish oil supplements is causing harm to ocean ecosystems.

What essential oils are safe for pets?

Essential oils should not be given to or applied to pets. There is no scientific evidence to support the claim that essential oils aid in medical conditions or symptoms. In addition, some essential oils can be toxic when touched, inhaled, or ingested by pets.

The Vetster Editorial Team is comprised of seasoned writers and communicators dedicated to elevating stories about Vetster, pets and their owners.
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