Deciding on Whether or Not to Add Vitamin C to Your Dog's Diet
Unlike humans, dogs 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 dogs.
What Are Vitamins?
Vitamins are a class of compounds first described in 1912 as “vital-amines,” or substances that are vital to life. A vitamin has five basic characteristics:
- It is an organic compound that is not a fat, protein or carbohydrate;
- It is part of an animal’s diet;
- It is essential in small amounts for an animal’s normal physiologic function;
- Without it, the animal will develop a deficiency syndrome; and
- It typically is not synthesized in sufficient quantities to support normal physiologic function.
Not all animals need all vitamins in their diets.
What Is Vitamin C?
Vitamin C, also known as ascorbic acid, L-ascorbic acid and cevitamic acid, is a substance found in many fruits and vegetables – especially tomatoes and citrus fruits like lemons, limes and oranges. It is also found in organ meats. Most animal species, including dogs and cats, synthesize their own vitamin C from glucose, with the help of an enzyme called L-gulonolactone oxidase. This is referred to as “de-novo synthesis.” These animals ordinarily don’t need to have vitamin C added to their diets. However, primates (including people), guinea pigs, fruit bats, insects and some birds and fish cannot make their own vitamin C because they lack L-gulonolactone oxidase. They have to get vitamin C from their food.
What Does Vitamin C Do?
Vitamin C is an antioxidant. It is best known for its role in the synthesis of collagen, a protein that is essential to the growth and development of skin, teeth, tendons, bones, cartilage and connective tissue. Vitamin C also is involved in drug, steroid and tyrosine metabolism and plays a role in the proper function of the immune system. Recent research suggests that vitamin C may reduce the risk of cancer of the stomach, mouth and lungs. It may also reduce the chance of tooth and gum disease and aid recovery from stress and exercise.
Do Dogs Need Vitamin C Supplementation?
Because healthy dogs make their own vitamin C in their livers, they probably don’t need extra added to their diet. If a dog has liver disease or unusually high metabolic requirements, it may benefit from additional vitamin C to keep up with its body’s needs. Some commercial dog foods contain vitamin C, presumably because of its natural antioxidant properties.
Supplementation with vitamin C is popular and widespread among health-conscious people, many of whom also give it to their dogs. Despite the absence of scientific studies confirming that extra vitamin C actually helps dogs, owners, breeders and veterinarians continue to debate the subject. Fortunately, there is not much evidence that extra vitamin C is particularly dangerous to dogs; whatever they don’t use is excreted in their urine in the form of oxalate. Elevated urinary concentrations of oxalate can increase the risk of stones developing in the urinary tract, especially in males.
How Much Vitamin C Should You Give a Dog?
Since Vitamin C is water-soluble, any excess is filtered out of the body through the urine. This does not mean, however, that overdosing is impossible. Too much C will often cause diarrhea and stomach upset. The amount that every dog can handle will vary depending upon the size and weight of the dog, as well as the dog’s individual GI tolerance. Dogs with sensitive stomachs may not be able to take more than 100mg per day, if any at all.
The guidelines for Vitamin C dosage in dogs vary, since most mainstream vets do not prescribe or encourage this type of supplementation. However, holistic vets recommend between 100 and 500 mgs per day depending upon the dog’s individual tolerances and needs. For dogs under 25 pounds, 100 mg should be plenty. Add 100 mgs per 25 pounds of weight. If the dog begins to experience stomach upset, reduce the dosage to by 50 mgs until you find the proper balance.
Dogs that consume a balanced diet of high-quality ingredients do not need to receive Vitamin C supplements, unless suggested by a vet. With the right balance of nutrition, the body of a dog will have all it needs to produce this vitamin on its own. However, many owners feel better knowing they are providing their dog with a little bit of extra ammunition to help the immune system do its job. If you have questions or concerns about the proper dosing or administration of a Vitamin C supplement, consult with a canine nutrition expert or a holistic veterinarian.