Hypothyroidism is the most common thyroid illness in dogs, characterised by an abnormally low production of thyroid hormone. It is thought that most cases are the result of destruction or deterioration of the tissue of the thyroid gland, commonly believed to be the result of an auto-immune disorder.
Symptoms may include the development of an overly dry coat or excessive shedding, lethargy and general dullness, weight gain, an increase in blood cholesterol levels, or even anaemia. Once diagnosed, (which may involve two or more stages of specific blood tests), the condition is relatively easily treated through the use of a drug called thyroxine, a synthetic thyroid hormone. This will need to be continued throughout the dogs life.