Hyperthyroidism is a hormonal condition in which the thyroid gland produces too much thyroid hormone. In the small animal world, cats are the most common to get this disease. Even more specifically, older cats are much more common than younger cats. The thyroid gland is responsible for the maintenance of metabolism among other things. A detailed history, physical examination, and blood tests can easily diagnose this condition.

The common clinical signs of hyperthyroidism is excessive weight loss despite an increased appetite and mood changes. Cats will occasionally exhibit excessive thirst and urination. It is not uncommon for a 10 pound cat to lose 3-4 pounds quickly. 

In order to diagnose hyperthyroidism, veterinarians check a total T4 level. A high level is diagnostic. A complete blood count and profile are necessary to rule out other conditions. A careful evaluation of the heart and blood pressure should be performed as hyperthyroid disease often leads to heart disease and hypertension. Once this condition is corrected, it is very important to continue to evaluate kidney function. The kidneys actually benefit from a hyperthyroid condition due to tremendous blood flow to the area. As the blood flow to the kidneys decrease with correction of the thyroid abnormality, the kidneys can decompensate leading to disease. In order to ensure adequate dosing, the thyroid level should be checked at least annually. 

Correcting an overactive thyroid can occur in several different ways. The most common method is a daily medication that slows the overproduction of thyroid hormone. This comes in the form of a tablet or transdermal ear medication. This is a life long therapy. This condition can be cured with more aggressive therapies such as surgery to remove the thyroid glands or iodine-radiation therapy. A new maintenance diet has shown significant promise with correcting this condition.