Hyperthyroidism is a common disease in older felines of all sizes

By LuAnn McLain

"Sade" is our cherished 14-year old Persian cat. She has a very sweet personality. Most of the time she is a typical Persian- laid back and beautiful.

After noticing behavior changes, suspecting she had lost weight, and seeing other health problems, we made some visits to the veterinarian. Blood work revealed an elevated thyroid output. Exploring options and checking information on the Internet, we discovered that thyroid problems in cats, especially older cats, are quite common.

We found centers throughout the US that are dedicated to treating thyroid problems in cats. None are in Montana.

An elevated thyroid, or hyperthyroidism, is caused by a tumor on the thyroid. According to statistics, 98% of the time the tumor is benign. It causes the thyroid gland to produce too much of the hormone. Thyroid hormones stimulate other systems in the body and help regulate things like body temperature.This condition causes most of the rest of the body systems and organs to be over stimulated. Symptoms include things like weight loss, behavior change, changes in appetite, greatly increased activity or greatly decreased activity. Other problems may be heart problems, drinking more water and using the cat box more, shedding, fever, diarrhea and osteoporosis.

Veterinarians trained in the specialty of treating this disease will likely be able to feel the enlarged thyroid. A healthy thyroid is not normally detectable.

Hyperthyroidism can actually be fatal if left untreated, so it is important to seek treatment. There are three main options.

A cure can be as simple as an injection. An injection of Radioiodine (I-131), basically radioactive iodine, is absorbed by the thyroid gland. The tumor portion is destroyed and the good portion of the thyroid is left unharmed. At least 98% of the cats treated with this are cured after one injection.

The cat has to remain in the clinic or hospital for an average of 7-10 days. This is because the cat will be releasing radiation and must not expose people or other animals to it. Once the cat is treated, it will stay in an isolated area with careful handling to prevent exposure to others. For this reason, only specialized treatment facilities can be approved to provide this treatment.

Once the cat has reached a safe and legal level of radiation release, she can be allowed to return home with special instructions for continued safe handling. The cat's thyroid function usually will be normal within a month of treatment.

With this treatment, the healthy thyroid tissue is not affected. The cat does not have to be anesthetized as she would for surgery. Also, the parathyroid glands are not affected as they can be in surgery. Most of the time after the injection, the cat will not even need thyroid supplementation.

The drawback of this treatment is that it is expensive. The entire treatment may cost as much as $600 - $900. For those of us living in Montana, the closest treatment facility is in Pullman, WA, at the School of Veterinary Medicine teaching hospital, so travel adds to the expense.

Treatments that can be provided locally also have a large cost. Anti-thyroid drugs can be prescribed for the hyperthyroid cat. There are a number of risks related to giving this drug. A pill must be given to the cat 1-3 times a day. Not an easy task, especially once the cat knows the pill is coming. As with any drug, there are risks of side effects. Nausea, vomiting, lethargy, lack of appetite, hair loss, and facial scabbing are noted side effects. There can be long-term damage to the liver and kidneys. White blood cells can be lost and the ability of the blood to clot can be compromised.There must be blood tests to monitor thyroid hormone levels and potential side effects when a cat is on the anti-thyroid medication. Pills and blood tests will run $400-$600 a year and must continue for the rest of the cat's life because the anti-thyroid drug does not cure the disease.

Surgery is the third option. The anesthesia is always a risk for a pet. Sometimes a second surgery is required and each surgery can be $600 and up. The parathyroid glands might be damaged or have to be removed and it can be difficult to identify and remove the entire tumor. Within a year and a half after surgery, a large percentage of cats will develop another tumor.

Surgery may only delay the need for more surgeries or the injection treatment.

Sade is now at Pullman and we are waiting for word that she can be released. Hopefully she will be at home resting peacefully by the time readers see this. We are hopeful her recovery will be complete and speedy!

Have a safe and happy week with your companion critters. If you would like to write to Pawsitively Pets, please send your letter to PO Box 1731, Havre, MT 59501.