6 min read

Antioxidants for Dogs


By Aurus Sy

Published: 06/08/2017, edited: 12/01/2023

Reviewed by a licensed veterinary professional: Dr. Linda Simon, MVB MRCVS

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As a doting pet parent, you’re always looking to provide your pup with the best care possible. Nutrition, of course, is a vital part of that. You may have heard of antioxidants and that they can be beneficial to your dog’s health. 

But what exactly are antioxidants and what do they do? Does your dog need antioxidant supplements or can they be obtained from natural food sources? 

You’ll find the answers to these questions and more below—read on to learn about antioxidants for dogs and how they can help your pup live a healthy and vibrant life!

What are antioxidants?

Antioxidants are substances that neutralize free radicals—compounds which are produced during oxidation. Oxidation is the chemical process that causes iron to rust, sliced fruits to brown, and oils to become rancid. It’s also a normal process that happens in your dog’s body (and yours). 

Oxidation occurs when your pooch exercises or breaks down food, so free radicals are constantly present in their body. At low levels, they’re harmless and even play a role in regular body functions such as fighting off pathogens. A certain amount of free radicals is actually necessary for keeping your pup healthy. However, too many spells trouble—and that’s where antioxidants come in.

pints of blueberries - antioxidants for dogs

What do antioxidants do for dogs?

Excessive free radicals can come from various sources including extreme exercise, inflammatory diseases, and external factors such as pollution, cigarette smoke, and sunlight. An accumulation of free radicals in the body can lead to oxidative stress, which can damage cells and DNA. This in turn can lead to increased risks of cancer and chronic diseases.

Antioxidants such as vitamin A, vitamin C, vitamin E, and selenium have the ability to counteract the harmful effects of free radicals. Here are some of the benefits of antioxidants for dogs:

Eye health

The antioxidants lutein and zeaxanthin (a carotenoid) support healthy vision by offering protection against free radical damage to the eye. They may help prevent glaucoma and cataracts as well.

Heart health

Antioxidants promote cardiovascular health by protecting the heart and circulatory system from oxidative stress. Vitamin C and omega-3 fatty acids reduce oxidative stress in blood vessels and promote proper circulation, while selenium helps keep the heart muscle healthy. 

Joint health

Joint issues like arthritis are common in older dogs. Antioxidants such as vitamins C and E help reduce inflammation and oxidative stress in the joints, improving comfort and mobility. Vitamin C is also crucial in the formation of collagen, the building block of cartilage and other connective tissues. 

Immune function support

Antioxidants help boost the immune system by protecting immune cells from oxidative damage and enhancing the production of lymphocytes, a type of white blood cell. A strong immune system enables your dog to keep infections and illnesses at bay. 


Over time, a dog’s body accumulates damage to cells and organ systems that are vital to the production of antioxidants, so an older dog may not be able to process and eliminate free radicals as efficiently as before. With their protective properties, antioxidants help maintain cellular health and improve the efficiency of systems, reducing the risk of chronic diseases and resulting in better health.

The recommended amount of each kind of antioxidant for dogs can vary and is still being studied.

Dr. Maureen McMichael, a professor at the University of Illinois College of Veterinary Medicine, recommends the following amounts:

  • Vitamin C (ascorbic acid) - 500 to 1,000 mg every 24 hours
  • Vitamin E (natural) - 400 units every 24 hours
  • SAMe - 20 mg/kg per day
  • N-acetylcysteine - 50 mg/kg
  • Ubiquinone (coenzyme Q10) - 2 mg/kg every 24 hours

Dr. Randy Kidd, a past president of the American Holistic Veterinary Medical Association, recommends the following amounts for a dog weighing 20 to 40 pounds:

  • Vitamin A - 2000 IU a couple times a week
  • Vitamin C - 250 mg per day
  • Vitamin E - 100 to 200 mg

The guaranteed analysis on most dog food labels won’t list the amounts of antioxidants included, but you’ll usually be able to spot antioxidants in the ingredients list. If you’re planning on giving your pup antioxidant supplements, consult your vet about the appropriate dosage first.

a spread of antioxidant foods

Healthy sources of antioxidants for dogs

Antioxidants can be found in a variety of foods, especially fruits and vegetables. The vibrant colors in fruits and vegetables usually indicate the presence of antioxidants, so the more colorful it is, the more likely it’s packed with antioxidants. 

Healthy sources of antioxidants for dogs include:

There is increasing evidence that antioxidants obtained from natural whole food sources are more effective than those taken in tablet or capsule forms. This is likely because antioxidants tend to work best in combination with other antioxidants, nutrients, and phytochemicals, so it’s a good idea to include antioxidant-rich foods in your dog’s diet.

Add small amounts of fruits and veggies to your dog’s normal food or offer them as snacks. Cooking and/or chopping fruits and vegetables up into small pieces can make them easier and more appealing for your dog to eat. You can also add them to homemade treats. Try several different foods to see what your pup enjoys the most, and feed them a variety so they get a mix of antioxidants. 

Golden Retriever dog eating watermelon

Antioxidant supplements for dogs

Does your pooch need antioxidant supplements? Dogs who can benefit from antioxidant supplements include canine athletes and working dogs, who may have elevated oxidative damage due to increased production of free radicals, as well as aging, stressed, or sick canines who may have weaker immune systems and need help eliminating free radicals.

Some vets feel that even healthy dogs could also use antioxidant supplements since they’re exposed to environmental pollutants and toxins that can generate free radicals. 

Antioxidant supplements for dogs include vitamins, minerals, amino acids, enzymes, herbs, botanicals, and other nutraceuticals. They come in various forms including tablets, capsules, liquids, soft chews, and powders. Some supplements provide a single antioxidant while others contain a blend of different antioxidants.

Studies on antioxidant supplementation in dogs have found the following benefits :

How often should I give my dog antioxidant supplements?

How often an antioxidant supplement should be given will depend on the type of supplement and your dog’s unique needs. Always consult your vet before giving any supplements to your pup.  

Potential side effects

Antioxidants are generally considered safe and side effects will depend on the type of supplement. Possible side effects are rare but can include:

  • Vitamin A - vomiting, drowsiness, irritability, peeling of the skin
  • Selenium - selenosis, a condition that causes intestinal upset, hair loss, and bone abnormalities
  • Mild stomach upset

Other considerations

As with anything, moderation is key. Consuming too many antioxidants can have negative consequences, including toxicity of a vitamin or mineral. Some antioxidants can interfere with other antioxidants as well if given in excess. All vitamins, supplements, and medications have the potential to interact with each other, so it’s important to tell your vet about everything your pup is currently taking.

And while antioxidants play a role in cancer prevention, some research suggests that antioxidant supplements may be counterproductive after a cancer diagnosis. Cancer cells generate free radicals rapidly; interestingly, a cell that accumulates too many free radicals can self-destruct. Some cells in the immune system and various therapies also produce free radicals to target cancer cells. So introducing high levels of antioxidants which neutralize these free radicals might do more harm than good. 

Pug dog with a banana peel on head

Antioxidants for Dogs: Recap

  • Antioxidants are substances that neutralize free radicals, which are harmless at low levels but have undesirable effects at excessive amounts.
  • Too many free radicals in the body can lead to oxidative stress, which can lead to increased risks of cancer and chronic diseases.
  • Antioxidants can help keep a dog healthy by protecting their cells and organs from oxidative damage.
  • Antioxidants are present in a wide variety of foods, especially colorful fruits and vegetables.
  • Working, aging, or sick dogs may need antioxidant supplements. Even healthy dogs can benefit from a supplement.
  • The dosage of an antioxidant supplement will depend on the type of supplement and the individual dog. Always consult your vet before starting any supplements.
  • While antioxidants are generally considered safe, they may interact with other supplements, medications, or conditions such as cancer. As with anything, moderation is key! 

Got more questions about antioxidants for dogs? Chat with a veterinary professional today to get fast answers—Wag! Vet Chat is available 24/7!

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