Within the last fifteen years, hyperthyroidism has emerged as a new disease in cats 10 years and older. In fact, it now ranks as one of the most common endocrine disorders in the cat, afflicting one of every 300 cats seen at the Animal Medical Center in New York City.

           It is not yet known whether feline hyperthyroidism is the result of a primary thyroid disorder, or whether some factor(s) may be stimulating the thyroid stands to produce an excessive amount of thyroid hormones.

Symptoms and Diagnosis

           Typical symptoms of hyperthyroidism include weight loss, increased appetite, hyperactivity, restlessness, increased fluid intake and urination, vomiting, diarrhea, and muscle weakness. Often the coat looks unkempt and dull. The heartbeat feels strong and rapid, sometimes with noticeable arrhythmia. If you own a middle-aged or older cat displaying these symptoms, you should schedule an appointment with your veterinarian. The only sign we see consistently in all hyperthyroid cats is weight loss. The other symptoms tend to appear later as the disease progresses.

           Because the symptoms can be suggestive of other diseases, your veterinarian will probably suggest a complete blood count, routine serum biochemical tests, and serum thyroid hormone concentrations to aid in a definitive' diagnosis.

           During the Physical examination the veterinarian will also feel the neck region to determine if the thyroid glands are enlarged, indicating hyperthyroidism. Either one or both glands may be affected. In approximately 50% of cats diagnosed as being hyperthyroid, both thyroid glands are diseased.

Treatment

           There are three basic forms of treatment available -- surgery, anti-thyroid drugs, or radioactive iodine therapy. Each form of treatment has its advantages and disadvantages. Your veterinarian's choice of treatment will be based on several factors, including the cat's age, and the presence of associated heart disease or other medical problems.

Surgery

           If your cat has a one-sided thyroid enlargement, surgery may be a good solution. Especially if he is hard to pill, if you’re away a lot, or if he requires increasing doses of the anti-thyriod pills (Tapazole). We have done this surgery on approximately 900 cats in the last 15 years. Most cats were over 12 and many were 12 – 16 years old. Survival rate has been 99.6%. The surgery is not very traumatic for the cat because it is basically a minor surgery done via a 1” long incision behind the “Adam’s Apple”. The cost all inclusive is approximately $600-800.

           If both thyroid glands are affected and the medication is problematic, as discussed above then the radioactive Iodine treatment might be a good solution.

Anti-thyriod Drugs

           Cats are treated with methimazole (Tapazole) which depresses the thyroids output. Normally this pill is given twice per day and about half of our patients will eat it ground in a favorite food. Adverse reactions can occur but are very rare. Most common of these are gastrointestinal signs – inappetance, vomiting and/or diarrhea. These G.I. signs are dose size dependent and often appear when the dose of Tapazole needs to be raised to 1 ¼ tab or 1 ½ tabs twice per day. We need to recheck thyroid levels initially at 2 weeks and if regulated then every 2-3 months. This is done via a simple painless blood tests.

Radioactive Iodine Treatment

           This treatment modality is expensive, but is sometimes appropriate especially if the patient is difficult to medicate, has both thyroids enlarged, and/or has already had one thyroid removed wherein the surgeon was unable to spare the BB sized parathyroid gland. Radiocat in White Plains can handle this radioactive iodine treatment and have your cat home in 3-7 days. Their number is 888 356-4131.