Hyperthyroidism (Thyrotoxicosis) is a very common condition among older felines.  A tumor of the thyroid gland causes the gladn to overproduce thyroxine, the hormone that refulates body metabolism.  This can cause the body to burn energy faster than the cat can consume calories.  It also puts a lot of stress on the heart and liver, and can be fatal if untreated.  The good news is that the thyroid tumor is usually benign and won't spread to other organs.

Symptoms of hyperthyroidism may include increased appetite, weight loss, restlessness, rapid heartbeat, increased water consumption, high blood pressure, and excess toenail growth.  Some cats also have diarrhea, scrufy coats and / or labored breathing.

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There are three ways to treat hyperthyroidism:

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Medical

The drug Tapazole (methimazole) is used to suppress production of the thyroid hormone.  This can be very effective, but must be given twice a day for the life of the cat.  Most cats do well on Tapazole but a few have problems such as comiting and not eating, and occasionally the drug may cause serious side effects.  Also, some cases do not respond well enough to Tapazole to control their symptoms.

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Surgical

Removal of the affected thyroid gland may cure the condition, but the surgery is difficult and can be dangerous in older cats.  There is a chance the tumor may grow back after the surgery.  Surgical treatment is much less common since the radiation treatment became available.

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Radiation

Pets of the Bay Area have comprehensive radiation therapy available only at Bay Area Veterinary Specialists. Services available include I-131 for hyperthyroidism and highly advanced image guided radiation therapy, utilizing the Bay Area's only Linear Accelerator for pets. With CT image guided treatment planning through a board certified veterinary radiation oncologist and sophisticated software, focused radiation can be delivered from outside the body to destroy tumors within the body. Because all iodine in the body goes directly to the thyroid gland, the cat is injected with radioactive iodine.  This destorys the tumor without damaging other organs.  This therapy is much safer and less invasive than surgery and is more effective.  After radioiodine treatment, your cat would normally not need any oral medication.  We have sent several patients to Dr. Turrel with good results.  Call our office to discuss radioiodine treatment as a possible treatment for your cat.

Cats with hyperthyroidism may also need to be treated for secondary heart disease or other problems caused by their hyperthyroidism or advanced age.