Hyperthyroidism is a disease that commonly affects older cats. Hyperthyroidism is caused by an increase in production of thyroid hormones (known as T3 and T4) from an enlarged thyroid gland in the cat’s neck. In most cases, enlargement of thyroid glands is caused by a non-cancerous tumor. Symptoms of hyperthyroidism include: weight loss, increased hunger, thirst and urination. Some people notice that their normally polite cat is now stealing food off the counter or plates, due to the increased appetite. Hyperthyroidism can be diagnosed from a blood test. There are a few different treatments available. 1. Medication, which does not cure the disease, but keeps the thyroid functioning at normal levels. This has to be given for the rest of the cat’s life. This medication is available in a few forms: pills, a cream that is absorbed through the skin, flavored liquid and flavored chew treats. 2. A prescription diet from your veterinarian. This diet restricts iodine. Healthy cats in the same household can eat this food as well, as long as some regular food is given to them every day. 3. I-131 treatment, which is an injection of radioactive iodine that travels to the tumor and destroys it. Healthy thyroid tissue is left intact. This is the gold standard of treatment.  In most cases only one treatment is needed. 4. Surgery to remove the tumor. This is not usually done. It seems to be a treatment of the past because there are less invasive options available. It is important to schedule an appointment with your veterinarian if your cat is showing any symptoms of hyperthyroidism. If left untreated the secondary problems caused by this disease can be serious. If treated early your cat can live a long happy life.