Hypothyroidism

Both adults and juvenile onset hypothyroidism results from lack of circulating thyroid hormone. Juvenile onset is so rare that only six cases are reported in the literature. Adult onset is primarily the result of lymphocytic thyroiditis ( an immune-mediated disease) or idiopathic atrophy of the thyroid, which means that the cause has yet to be determined. Both forms probably affect the Alaskan Malamute equally.

Many breeders feel the incidence of thyroid problems is fairly high. However, until recently, no central collating organisation has collected statistics or compiled reports, so the belief is only speculative. The open thyroid registry began in 1996 by the OFA should provide valuable and valid information about the problem at last.

Recognising the clinical signs is important. Most of them related to the involvment of thyroid hormone in the basic metabolism. The most common signs are lethargy and dullness, hair loss and obesity. Some animals also have no heat cycles or abnormal ones, darkening of the skin, and/or cold intolerence, and a few have a lowered heart rate. The gradual degeneration of the thyroid means that signs of the disease may not be recognisable as such until the dog is between four and ten years of age.

Diagnosis of hypothyroidism by blood tests (T3, T4, and Free T4 and TSH) should be carried out on any suspected animal. Treatment is with a synthetic hormone given orally.

Immune-medicated hypothyroidism results from abnormalities of the dogs immune system. Other causes of thyroid atrophy are not known and may possibly be of familiar origin. In all breeds, certain lines of dogs have been incriminated as being "carriers," but no concrete proof supports this contention. Until absolute evidence of the underlaying mechanism is found, it should be assumed to have soem genetic origin. Affected individuals should not be used in breeding programs.