Hypothyroidism is a deficiency of thyroid hormone. Because the thyroid gland sets the rate at which cells burn energy, a deficiency of thyroid hormone leaves pets dull and listless in body and soul.
Dogs frequently develop hypothyroidism. In fact, hypothyroid disease in dogs is the most common endocrine disease of dogs. Between 1 in 150 and 1 in 500 dogs has hypothyroidism. Cats, on the other hand, rarely develop hypothyroid disease, although they frequently develop the opposite disease—hyperthyroidism.
Among the dog breeds predisposed to hypothyroidism are: Golden Retriever, Doberman Pinscher, Irish Setter, Great Dane, Airedale Terrier, Old English Sheepdog, Dachshund, Miniature Schnauzer, Cocker Spaniel, Poodle and Boxer.
Hypothyroid disease affects your dog's entire body. The skin is often smelly, dry, and dull. The hair falls out and your pet gains weight. Some pets don't experience normal heat cycles or develop normal sperm. Most dogs seem mentally dull. Fortunately, hypothyroid disease is easily treated.
Some veterinarians believe the increase in hypothyroid disease parallels the increase in the number of vaccines given. They point out that vaccines stimulate the immune system, and that many dogs develop a form of thyroid disease where their immune cells attack the thyroid (lymphocytic thyroiditis) until it is no longer able to function. Because of this, many veterinarians recommend that dogs be vaccinated as infrequently as necessary to provide disease protection. For some pets that will mean they need only a single vaccine as an adult to be protected for life. Other dogs may need vaccines every few years.