How Dogs Produce Vitamin C

Unlike humans, dogs typically do not need additional vitamin C (ascorbic acid). Dogs, as well as many other animals, manufacture vitamin C through their glandular systems. A healthy dog typically produces about 18mg of vitamin C for every pound of body weight (for example, a 50-lb. dog produces about 900mg per day), providing a continued concentration of ascorbic acid in the dog's system. Some veterinarians suggest additional vitamin supplements, based on the dog's health. But giving too many vitamins to a dog can have serious repercussions.

A dog synthesizes as much vitamin C as it typically needs through its liver using trace minerals in takes in through its diet. People either never had this ability, or lost it through the ages. When vitamin C supplements are added to a dog's diet, the dog's own ability to produce vitamin C is shut down, perhaps permanently. In addition, the liver and kidney of a dog do not handle well an additional concentration of ascorbic acid. The dog's system works to rid itself of the overabundance of ascorbic acid, causing stress to the organs. A long-term excess of vitamin C can result in kidney and liver damage, which can threaten the dog's life.

Natural sources of vitamin C are potatoes, cauliflower, tomatoes, berries and citrus fruits. Giving a dog a few pieces of fresh fruit on occasion (no grapes, though, which can cause kidney damage) will not upset the balance of vitamin C in its system and will not cause its organs to shut down. Signs of a vitamin C deficiency include becoming more susceptible to infections, obvious joint pain and slower healing. Signs of too much vitamin C, which is a natural laxative, include diarrhea. Excessive doses can contribute to kidney stones.

Dogs with specific health situations, such as infections and injuries, can benefit from vitamin C supplements. A veterinarian can suggest an amount and for how long the dosing should continue. In this case, the vitamin boost is targeting a specific problem. Typically, the supplements are stopped after a few days.

An over-the-counter buffered vitamin, such as Ester-C calcium ascorbate (a version of vitamin C with a calcium component that is typically easy for a body to absorb, providing 114mg of calcium per 1,000mg of asborbic acid) can be beneficial when a dog suffers an injury or has a respiratory problem. It can work as an antioxidant and anti-inflammatory. In one study published in 1990 in the "Norwegian Veterinary Journal 102," Dr. Geir Erik Berge, a veterinarian in Oslo, Norway, administered Ester-C to disabled dogs during a six-month period. After several days, most of the dogs showed marked improvement.

Good-quality dog food, whether from a veterinarian, specialty shop or grocery store, will provide the nutrients a dog needs. From this food, a dog's liver synthesizes the Vitamin C it needs to function well.