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CAT CHAT

FELINE HYPERTHYROIDISM

By Nancy Marano

Older cats are subject to special health problems. One of the most common is feline hyperthyroidism. Although the symptoms are disturbing to cat and owner alike, this is a highly treatable disease.

Dr. Stephen Hopkins, DVM, Academy Animal Clinic in Albuquerque, describes typical symptoms. “The cat has a ravenous appetite but continues to lose weight and drinks a lot of water causing frequent urination. These cats are very nervous. They yowl and make sounds they never made before because they don’t feel good.”

Other physical signs are unhealthy skin and haircoat, possible vomiting and diarrhea, hyperactivity, increased heart rate, and enlargement of the thyroid gland.

The thyroid gland, located at the base of the neck, releases hormones to regulate the body’s basal metabolism. Hyperthyroidism is caused by the overproduction of thyroid hormones. The cat’s metabolic and heart rate increases so the cat burns itself out on fast forward unless the problem is corrected.

To diagnose hyperthyroidism the veterinarian palpates the cat’s neck for an enlarged gland, checks for dramatically increased heart rate, and uses blood tests to reveal elevated thyroid hormone levels. Sometimes a T3 suppression test, thyroid scan, or biopsy is suggested for conclusive diagnosis.

“We have three methods to treat hyperthyroidism,” Dr. Hopkins said, “and I’ve had good success with all three.”

Oral medication: The cat takes three methimazole tablets daily for the rest of its life. This is an anti-thyroid medication, which reduces the amount of thyroid hormone produced. It is not a cure for the disease but a way to manage symptoms.

Surgery: Removal of the thyroid gland. This treatment is usually followed by thyroid hormone supplementation given daily in pill form. Regular blood tests are needed to check thyroid hormone levels.

Radioactive iodine therapy: The preferred treatment due to its 90%-95% cure rate. No follow-up treatments are required, and there are no side effects. Radioactive iodine destroys tumorous thyroid tissue wherever it occurs in the body. One subcutaneous injection is given. The cat remains in the hospital 7-14 days until it reaches the legal radiation level. Few facilities are licensed to use radioactive materials, but New Mexico cats are lucky because Dr. John Romero, of Santa Fe’s Aardvark Veterinary Clinic, is licensed to perform this procedure.

Consult your veterinarian immediately if your cat displays any abnormal behavior.
Early diagnosis and treatment is the best defense against hyperthyroidism and other diseases.

Nancy Marano is a freelance writer living in Albuquerque.

Note: This article first appeared in the Summer 1998 issue.

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