The most common symptoms of hypothyroidism in dogs include poor hair regrowth after being clipped and hair loss on the neck, chest, sides, thighs and tip of the tail. Some other symptoms that may be seen are weight gain, lethargy, cold-intolerance and lack of heat cycles in female dogs.
Hypothyroidism is a deficiency of the thyroid gland. The thyroid gland normally produces adequate quantities of hormones to control the metabolic rate; however, in a dog with hypothyroidism, the gland produces insufficient amounts, which results in metabolic rates below normal. This deficiency is most commonly caused by the destruction of thyroid tissue due to autoimmune thyroiditis. Hypothyroidism is the most common skin disease in dogs. It is known to be an inherited disease that affects middle-aged dogs of all breeds, but is most commonly seen in medium- and large-size breeds. Retrievers, sheepdogs and greyhounds are among the most commonly affected breeds.
Dogs with hypothyroidism may develop other problems as a result of the disease, such as deafness, ulcers, anemia, chronic constipation and strokes. Some dogs have been discovered to have hypothyroidism after testing revealed the presence of elevated cholesterol during routine blood screenings and after viewing aggressive behavior changes. Generally, hypothyroidism is diagnosed by a simple blood test administered because the dog's symptoms correlate with those of the disease. Hypothyroidism is a permanent disease with no cure but can be treated with daily hormone-replacement medication.