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Vitamin C Supplementation for Dogs

Vitamin C is one of the most popular vitamins used for its antioxidant abilities and immune support in humans. Since humans cannot produce vitamin C, we must get it from the diet. Deficiencies in humans can lead to serious and even fatal diseases, such as scurvy. Unlike humans, dogs’ bodies can produce vitamin C, but in spite of this, my experience has taught me that there are many reasons to supplement a dog’s diet with additional vitamin C.

Let’s take a look at some of the reasons vitamin C supplementation is an important part of your dog’s health as well as how you can find the right supplement for your pet.

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The Controversy of Vitamin C Supplementation for Dogs

Since dogs can make their own vitamin C, so it is presumed that they don’t need to get it from their diet like people do. In a perfect world, this might well be the case. However, the problem is that we live in an extremely toxic world. Let’s take a look at just some of the toxins modern companion animals are exposed to on a daily basis:

  • Air pollution (indoor and outdoor)
  • Bacteria, viruses and chemicals in tap water
  • Electromagnetic radiation from computers, cells phones and television sets
  • Lawn and garden chemicals, pesticides and herbicides
  • Medications
  • Plastics in toys and food bowls
  • Processed pet foods
  • Topical “spot on” chemical flea and tick preventives
  • Vaccines

Commercial pet foods alone can contain a myriad of toxic ingredients, such as chemical colors, flavors and preservatives that tax the immune system.

In my experience working with private clients, I know that many modern companion dogs have the physiological stress of dealing with chronic illness. They also may suffer from the emotional stress that comes with living as part of a modern family. After all, our dogs are emotional sponges that bare the burden of any negativity occurring with their human family.

To help our dogs stay resilient to the toxins, illnesses and stress they are exposed to daily, I recommend vitamin C supplementation along with as much home cooked, fresh food as possible.

The Benefits of Vitamin C Supplementation for Dogs

Vitamin C and Infections

Many animal studies have shown numerous health benefits of vitamin C supplementation. In fact, one study of vitamin C supplementation for dogs found that vitamin C supplementation had therapeutic benefits for dogs who were suffering from the canine distemper virus.1 The study was looking at the relationship Vitamin C supplementation had on infections. The same study also found that typically only 5-10% of dogs with the canine distemper virus recover with signs of central nervous system disturbances. However, in the dogs receiving vitamin C, 44% of the dogs recovered.

Another animal study conducted on guinea pigs showed that vitamin C has significant benefits for animals battling infections. This study showed that vitamin C improved the outcome of infections such as mycobacterium tuberculosis, fusobacterium necrophorum, as well as candida albicans.

Vitamin C and Everyday Toxins

When the body is chronically exposed to the toxins of everyday life, it can cause significant stress on the immune system. As we just discussed, dogs are exposed to toxins in commercial dog food, vaccines, certain plastic chew toys, pesticides and fertilizers used in grass, contaminated water and environmental pollution. When the body is stressed, glucocorticoids (corticosteroids) that are present in the adrenal glands increase, which suppresses the immune system. Vitamin C plays an important role here because it can help control the synthesis of corticosteroids by reducing the amount circulating in the body.2 Vitamin C can help keep the immune system healthy by preventing the corticosteroids from weakening the immune system as a response to stress.

Vitamin C can also help combat free radicals in the body often present from toxin exposure and regenerate antioxidants.2 Vitamin C can also act as a free radical scavenger. This is crucial, as free radicals can lead to chronic disease and can damage cells and impair the immune system.

Vitamin C and Joint Health

Vitamin C plays a role in boosting the health of collagen, which is essential for maintaining joint health. This can make vitamin C a great supplement for dogs suffering from any type of joint disease.

Vitamin C Synthesis Varies from Animal to Animal

Studies have also shown that the synthesis capacity of vitamin C varies greatly from animal to animal. This means that even though dogs can make their own vitamin C, not all dogs may be able to make sufficient amounts. For example, a dog’s ability to make vitamin C decreases with age, while at the same time susceptibility to disease increases. This means that senior dogs are prime candidates for vitamin C supplementation.

What to Look for in a Vitamin C Supplement

The first thing you want to think about before buying a vitamin C supplement is what form you are going to buy. Ascorbic acid is the most popular form of vitamin C. It is the isolated molecule that was discovered actually prevented scurvy. However,  it is not always well absorbed and can cause digestive upset. Since it is a chemical isolation, ascorbic acid may also be missing some of the synergistic nutrients that make vitamin C found in whole food effective.

There are other forms such as the salt forms of vitamin C like sodium ascorbate that are known to be less harsh on the system. These forms are also more absorbable. Dr. Belfield, the veterinarian who ran numerous studies on the benefits of vitamin C in dogs with distemper, allergies and hip dysplasia used sodium ascorbate in many of the studies.3 However, bear in mind that vitamin C bound to sodium will also increase a dog’s sodium intake, which is contraindicated for certain conditions such as kidney disease and hypertension.

Another form, calcium ascorbate – known as ester-C – is gentler on the stomach because it has a neutral pH.

Liposomal vitamin C is another form, which is ascorbic acid mixed with a fat source to increase bioavailability. Beware, however, as the fat source is typically soy lecithin and, an ingredient that we want to avoid giving dogs. Some forms do contain sunflower rather than soy, however.

Whichever form you select, be sure to purchase a pure vitamin C product without any fillers or unnecessary added ingredients, such sweeteners, artificial colors or flavors. You can look for a product labeled as USP pure, which stands for the United States Pharmacopoeia; any supplement with this label has been deemed pharmaceutical grade and is reviewed for purity.

Vitamin C Supplementation for Dogs: Fresh is Best

Along with supplementation, I always recommend a fresh food diet for your dog, and if you are not ready to take the leap into 100% home cooked food, adding some home cooked food to your dog’s diet can be very beneficial. Fresh food contains vitamins and minerals in their whole form. Nutrients from whole foods are always preferable to synthetic vitamins and minerals sprayed onto commercial pet foods. Not to mention the fact that you will be reducing the number of toxins your dog is exposed to when you feed fresh food.

Some dog-friendly foods that are rich in vitamin C include:

  • Acerola powder
  • Asparagus
  • Broccoli, Brussels sprouts, cauliflower, kale (avoid feeding these foods to hypothyroid dogs)
  • Camu-camu powder
  • Green pepper
  • Kiwi
  • Mango
  • Oranges (beware of amounts due to possible stomach upset)
  • Papaya
  • Parsley
  • Peas
  • Pineapple (limit amounts due to possible stomach upset)
  • Red pepper
  • Sweet potatoes

Vitamin C Supplementation for Dogs: Dosage and Precautions

Older dogs, dogs with a specific health condition or those with high exposure to toxicity will require a higher dose of vitamin C than healthy dogs. Recommended dosages vary based on the therapeutic aim as well as by the practitioner.

Dr. Richard Pitcairn advises giving 100 – 500 mg of vitamin C daily, depending upon the animal’s size.

Bear in mind that too much vitamin C will cause diarrhea and that individual tolerance levels vary, so start your dog off with a conservative amount and increase slowly, backing off if your dog shows any signs of digestive upset.

Vitamin C Supplementation for Dogs: Conclusion

Vitamin C supplementation for dogs is a great way to support the immune system, fend off free radicals, battle infections, decrease inflammation, help defeat cancer, promote joint health and give the body a boost during times of stress. If you would like to learn more about the specific studies that were done on the effects of vitamin C in animals, I have linked to each of the studies mentioned in the reference section in the body of the article.

As always, I hope that this information helps your companion animal to live the longest, healthiest life possible so that you can enjoy many happy years together.

(1) Harri Hemila (2017). Vitamin C and Infections. Retrieved January 3, 2018 from
(2) Vitamin C. Properties and Metabolism. Retrieved January 3, 2018 from
(3) Wendell O. Belfield: Veterinarian. Retrieved January 3, 2018 from

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