Dietary Supplements in Dogs and Cats with Heart Disease
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Dietary Supplements in Dogs and Cats with Heart Disease

by Lisa M. Freeman, DVM, PhD, DACVIM (Nutrition)
Jul 28, 2023

What are Dietary Supplements?

Products that are eaten to “supplement” the diet. Some examples include vitamins, minerals, herbs, amino acids, or probiotics. Supplements can come in tablets, capsules, powders, liquids, and other forms.

Why Might Dietary Supplements be Used in Dogs and Cats with Heart Disease?

Certain dietary supplements may be beneficial in some types of heart disease. This could be to correct a nutrient deficiency or to have effects beyond their nutritional properties. However, because supplements can have risks, it’s important to select them carefully, to use the right dose, and to use a product with good quality control. This is why it’s important to talk to your veterinarian or cardiologist before starting any dietary supplements. 

Risks of Dietary Supplements

While some dietary supplements may have benefits, they all have potential side effects. Therefore, supplements are not right for every dog and cat with heart disease. Although supplements are thought to be safe because they are “natural,” this is not always true. Supplements can cause pets to get sick, so it is very important to use supplements that have a low risk for side effects. Even if a supplement is safe for humans, it may not be safe for pets because they metabolize some supplements differently. Even if the supplement is safe by itself, there may be dangerous interactions when it is used in combination with certain heart medications.

Unless your pet has been diagnosed with a specific nutrient deficiency, supplements should not be used in place of recommended heart medications. Discontinuing heart medications without the recommendation of your veterinary team can be dangerous.

Should Testing be Done Before Starting Supplements?

Veterinarians can perform blood tests to test for deficiencies of certain nutrients. One of the most common deficiencies that we test for is taurine, an amino acid. Blood carnitine levels also can be measured, but this requires more specialized testing. If your pet is eating certain types of diets, other nutrient deficiencies that can cause heart disease are possible. Diets of concern include homemade diets (unless formulated by a Board Certified Veterinary Nutritionist and the recipe is strictly followed), vegetarian/vegan diets, or over-the-counter diets not designed to be complete and balanced (the label will read “for intermittent or supplemental use”). Testing for deficiencies of these other nutrients is possible, but usually we focus more on careful review of the diet. This can give us clues to which nutrients are likely to be deficient. Comprehensive nutritional blood tests, while appealing, are not accurate in figuring out whether your pet is getting the right levels of nutrients.

What are Common Supplements Used in Pets with Heart Disease?


Taurine is an amino acid which, if deficient, can cause a heart disease called dilated cardiomyopathy . Taurine deficiency is most often seen in cats because, unlike most other species, cats require taurine in their diet. Good quality, nutritionally complete and balanced commercial cat foods contain plenty of taurine. However,  diets that are not complete and balanced (labeled for intermittent or supplemental use), vegetarian/vegan diets, or homemade diets can be too low in taurine. If cat is diagnosed with DCM, blood taurine levels can determine if they are deficient. If your cat is taurine deficient, taurine supplements will be prescribed to help treat the disease.

Dogs, unlike cats, do not need to consume taurine if they have enough of the building blocks of taurine in the diet. However, certain breeds, such as Cocker Spaniels, Newfoundlands, and Golden Retrievers, appear to be predisposed to taurine deficiency. If your dog is diagnosed with DCM, your veterinarian or veterinary cardiologist might measure taurine levels in the blood or recommend taurine supplementation.

Most dogs with the current episode of diet-associated heart disease do not have low taurine levels. However, even without a deficiency, there may be mild benefits of taurine in dogs with DCM. Taurine is a safe supplement as long as a good quality brand is used. As with all supplements, it is important to get recommendations from your veterinarian for a specific dose and brand that has independent quality control testing.


Carnitine is a nutrient that is important for energy production in the heart. Most dogs with DCM do not have carnitine deficiency, but it can sometimes occur. L-carnitine supplementation may have some mild benefits in dogs with DCM even if they don’t have a deficiency by helping with energy production in the heart. It is generally a safe supplement and causes few side effects, although it can occasionally cause vomiting or diarrhea.

Omega-3 Fatty Acids from Fish Oil

Omega-3 fatty acids are a special type of fat that can help reduce inflammation in the body and reduce muscle loss in pets with heart disease. In people, omega-3 fatty acids may help prevent coronary artery disease, a disease that does not occur in dogs and cats. Therefore, in dogs and cats, omega-3 fatty acids are not effective as a “preventative” for heart disease.

Fish oil is often recommended for dogs and cats with congestive heart failure, especially those with muscle loss or reduced appetite. Fish oil supplements can also be used (in addition to appropriate medication) in dogs with some abnormal heart rhythms (arrhythmias). Fish oil is relatively safe, but it is not right for every pet. Veterinarians may avoid fish oil supplementation in animals with bleeding problems, with certain digestive issues, or those already eating a diet high in omega-3 fatty acids.

Fish oil may be purchased over the counter at almost all human pharmacies, but the dose, other ingredients, and quality of the products vary widely. Therefore, it is important to talk to your veterinarian for specific recommendations.

Coenzyme Q10

Coenzyme Q10 is a compound produced naturally in the body. It works as an antioxidant and helps the heart muscle cells make energy. Some studies in people – but not in dogs or cats – suggest that coenzyme Q10 has some benefits in DCM. In the most common heart disease affecting dogs, coenzyme Q10 might have some benefits in dogs with more advanced disease.

The dose of coenzyme Q10 depends not only on a dog’s size but also on the form of coenzyme Q10 (ubiquinone or ubiquinol). Therefore, it is important to talk to your veterinarian or cardiologist about whether coenzyme Q10 is appropriate for your dog and, if so, about the recommended form, product, and dose.

Other Antioxidants

Antioxidants help to rid the body of harmful compounds that can damage cells. In pets with congestive heart failure, more of these harmful compounds are produced while the body is also making fewer antioxidants to combat them. Antioxidant supplementation might help bring the body back into balance and lower the stress placed on the heart. However, some antioxidants can be harmful, and many products do not have good quality control. Be sure to talk to your veterinarian before starting any antioxidant supplements.

Other Supplements

A variety of other supplements have been recommended by various sources for pets with heart disease. However, the evidence for effectiveness and safety for these other supplements is much weaker compared to the supplements listed above.

How to Safely Select Supplements for your Pet

If you are interested in using supplements, the first step is to talk to your pet’s veterinarian or cardiologist about whether supplements are appropriate for your pet. This will depend on your pet’s age, type and stage of heart disease, other medical conditions, diet, medications, and a variety of other factors. 

If you and your veterinarian decide that supplementation is right for your pet, it is important to understand that dietary supplements in the United States (whether for humans or pets) are regulated very differently than drugs. Unlike drugs, the United States Food and Drug Administration (FDA) does not review the safety, effectiveness, or quality of supplements before they are sold. Therefore, consumers cannot assume that dietary supplements on the market are safe, effective, or have good quality control.

The effectiveness of dietary supplements is not often well-proven with research studies. Most pet supplements are used based on theory, anecdote, or data from other species. It’s also important to give the right dose to pets, which shouldn’t just be based on the human dose.

Even if a supplement is safe and effective, the quality control of supplements can be highly variable. That means that if you buy a supplement that is supposed to contain 100 mg of a certain nutrient per tablet, it may contain 100 mg, but it also could contain 500 mg or nothing at all! Supplements can also be contaminated with heavy metals or other substances.

One good option to help ensure good quality control in the United States is to use dietary supplements that have the United States Pharmacopeia Dietary Supplement Verification Program logo. This group tests human dietary supplements for ingredients, concentrations, contaminants, and whether tablets dissolve correctly.

Combination supplements (a mixture of multiple nutrients marketed for heart disease) often do not have optimal levels of each individual nutrient, and it can be difficult to maintain quality control of each ingredient. Therefore, supplementation of individual nutrients is recommended rather than combination products.

Especially for pets with heart disease, it is important to talk to your veterinarian before starting any supplement. There can be interactions between supplements and heart medications, or the supplements may be too risky to use. If your pet is already taking supplements, provide this information to your veterinarian along with the rest of your pet’s diet history.

The bottom line on dietary supplements: Talk to your veterinarian and limit supplement use to those that have evidence for benefits and low risks for side effects. Only use specific products that have independent testing of quality control at the optimal dose for your pet


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