Feline hyperthyroidism is a relatively common endocrine disease in cats. This condition occurs when one or both of the thyroid glands are overactive. The disease usually affects middle-aged to older cats and will cause heart failure and eventually death if left untreated.

Causes

One of the most common causes of feline hyperthyroidism is the occurrence of adenomas in the thyroid gland. Adenomas are groups of non-cancerous cells that form inside the gland. Feline hyperthyroidism can also be caused by the growth of cancerous cells, but it is very rare.

Symptoms

The thyroid glands in your cat are responsible for controlling the metabolic rate. Therefore, a cat with feline hyperthyroidism will have an increased thirst and appetite, but still lose weight rapidly. Your cat will also be hyperactive. Feline hyperthyroidism can also cause gastrointestinal symptoms such as diarrhea and vomiting. Arrhythmias, congestive heart failure, and an increased heart rate are also common symptoms.

Diagnosis

Diagnosis of feline hyperthyroidism is commonly based on a blood test designed to measure the level of thyroid hormone. However, the level can vary dramatically over time. When suffering from feline hyperthyroidism, your cat may also have an enlarged thyroid gland which the veterinarian may be able to feel it.

Treatment

There are basically three methods of treatment for feline hyperthyroidism. They include drugs, surgery, and radioactive iodine. Antithyroid drugs come in the form of pills and must be administered once or twice daily for the life of your cat. If medication is ever discontinued, the symptoms of feline hyperthyroidism will return quickly.

Feline hyperthyroidism can also be treated with surgical removal of one of both of the thyroid glands. However, some thyroid tissue may be in other areas of the chest and neck, so surgery may not always treat the condition. The final treatment of feline hyperthyroidism is radioactive iodine. The iodine destroys all thyroid tissue in the body. Although usually the most effective, it is also the most expensive method of treatment and requires that your cat be hospitalized.