In the early 1900s, ascorbic acid was isolated and identified as the nutrient that prevented scurvy. Humans, it was discovered, are among the few animals that cannot manufacture vitamin C in their own bodies, and must obtain it from an outside source (fresh fruits, vegetables, or vitamin C pills) on a regular basis in order to avoid illness.
Dogs, however, can produce vitamin C in their bodies, and because of this ability, nutritionists have long considered it unnecessary to add C to a dog’s diet. Until recently, few dog food makers added vitamin C to their products – or if they do, it was for the preservative action of the vitamin, rather than its nutritive value.
Vitamin C benefits the sick and the stressed
This may be appropriate when dealing with healthy unstressed animals, but recent clinical observations indicate that when dogs are sick or stressed, they can rapidly deplete their bodies’ output of vitamin C. A 1942 study noted that dogs with skin diseases usually have very low amounts of vitamin C in their blood.
Other researchers have found the blood levels of vitamin C to be low – and even non-existent – in dogs with fevers and dogs who have exercised to their limits (sled dogs after a race, for example, or hunting dogs in the middle of hunting season).
Stress is the best-known cause of vitamin C depletion in dogs. Physical stress comes in many forms: gestation, lactation, growth, hard work (dogs used for herding, hunting, tracking, etc.), vaccinations, injuries, tail-docking or ear cropping, or illness. Emotional stress, whether caused by relocation, weaning, or demanding training, can also deplete this reserve. In fact, researchers can measure the level of stress a dog experiences by measuring the degree of depletion of the vitamin in the dog’s blood.
Conversely, many studies have found that dogs (as well as humans) that are supplemented with vitamin C show greater resistance to disease, and a better ability to recover from injuries or illness.
According to the “Encylcopedia of Nutritional Supplements,” by Michael T. Murray (1996, Prima Publishing), vitamin C improves immune function by enhancing white blood cell function and activity. It also increases the blood levels of interferon (the body’s natural antiviral and anticancer compound) and antibodies (proteins that bind to and destroy foreign material such as bacteria, viruses, and toxins).
Vitamin C is commercially available by itself or combined with other nutrients in a number of forms.
Today, vitamin C is routinely prescribed by holistic veterinarians for a number of illnesses, including cancer, kennel cough and other respiratory infections, abscesses, and other bacterial infections. Due to its important role in maintaining the health of collagen, it appears to be especially helpful for slowing – and some say, reversing – degenerative joint disease, hip dysplasia, and spinal disorders.
The use of vitamin C as a preventative and immune booster are also celebrated. Some veterinarians suggest giving C to dogs before and after vaccination, to dogs that have been exposed to contagious diseases, to pregnant and lactating dogs, and for healthy teeth and gums.
According to Belfield, young dogs and old dogs can benefit the most from routine vitamin C supplements. Due to the extensive stresses faced by puppies and young dogs, such as numerous vaccinations, surgical procedures on dewclaws, tails, and ears, and the demands of rapid growth, he suggests that all young dogs receive C.
As they get old, dogs become less proficient at producing their own supply of vitamin C, and more in need of antioxidants. Administering vitamin C to even very old and feeble dogs, says Belfield, can reinvigorate and strengthen them.
The average dog normally produces about 18 milligrams of vitamin C per pound of body weight per day. Therefore, for a dog that is free of clinically significant symptoms but is experiencing unusual stress, supplementation with about that much C per day appears be a conservative maintenance dosage. (About 500 milligrams for a 28-lb. dog daily.) To increase absorption, veterinarians recommend splitting the total daily dosage into several feedings during the day.
However, many holistic veterinarians routinely suggest maintenance doses that are three to four times that amount. They explain that modern, domestic dogs need more vitamin C than the theoretical “natural” dog, since their bodies must deal with so many challenges: stress, pollution, chemicals and pesticides, and poor diets, to name a few.
Too much vitamin C, especially if given in one dose, will cause diarrhea in dogs. What amount is too much varies from dog to dog, so, when administering the maximum amount of C for a therapeutic (not just maintenance) dose, many veterinarians will suggest that you increase the dose in 100-500 milligram-per-day increments until the dog develops diarrhea, then reduce his daily dose to the previous day’s dose. (This is often referred to as dosing to “bowel tolerance.”)
It’s important to remember that a healthy, happy dog with a quality diet and little stress probably has no need of supplementation with vitamin C. However, if stress, illness, or age causes a dog’s need for vitamin C to outstrip his ability to produce it, supplementing him with C is a sensible choice.