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Supplementation With Vitamin C is Not Necessary for Most Pets

October 23, 2012

Supplementation with extra vitamin C is both popular and widespread among health-conscious people. However, unlike humans, dogs and cats manufacture their own vitamin C in the liver.  Despite this fact, many pet owners and veterinarians continue to debate the need for extra dietary vitamin C in pets.

Vitamin C is necessary for the production of  proline and lysine, two amino acids necessary for the formation of a substance called collagen. Collagen is a primary constituent of bone, teeth and connective tissue fibres, and is produced during skeletal growth and development. Most veterinarians believe that unless inadequate amounts of vitamin C are made by the liver or there is an unusually high metabolic requirement, supplementation of the diet with vitamin C is unnecessary.

Vitamin C may occasionally be included in a pet food because of its ability to act as a natural antioxidant. However, its effectiveness as an antioxidant is limited unless it is combined with other antioxidants such as vitamin E. 

There is some controversy about whether or not supplementation of a canine or feline diet with vitamin C is necessary, particularly during times of increased demand. However, no studies at present support the need for vitamin C supplementation for the average dog or cat, nor for the working or stressed animal.

In humans, the general belief is that vitamin C is, at best, beneficial and at worst, harmless.  Vitamin C supplementation in dogs and cats is also relatively safe. Suggested levels in dogs at which you are not likely to cause any harm are 25-100 mg of sodium or potassium ascorbate daily per dog. Larger doses are not recommended. No levels have been suggested for cats.

Unlike humans, however, vitamin C supplementation may be harmful under certain circumstances. For example, excess ascorbic acid is excreted in the urine as oxalate and elevated concentrations of urine oxalate may contribute to the formation of bladder stones in the urinary tract.

If you are feeding a nutritious, well-balanced commercial diet to your dog (or cat), there is really no need to provide a vitamin C supplement, and there is likely very little benefit in doing so.