What is the function of normal thyroid glands and thyroid hormones?

There are two thyroid glands located on the neck on either side of the trachea. Thyroid glands secrete thyroid hormones that regulate metabolism.

How do hyperthyroid thyroid glands function differently?

ALL cats with hyperthyroidism have a thyroid tumor in one or both thyroid glands. Most (roughly 98%) of thyroid tumors that cause hyperthyroidism in cats are benign or non-cancerous. Hyperthyroid cats will produce too much thyroid hormone which increases metabolic rates causing many body systems to work harder than normal. All thyroid tumors in hyperthyroid cats are made up of thyroid cells that grow and function at an uncontrolled rate. This makes cats’ thyroid glands grow larger and larger with time.

What are the clinical signs of hyperthyroidism?

• Weight loss
• Increased appetite
• Vomiting
• Diarrhea
• Increased drinking and urination
• Matted hair coat/ unkempt appearance
• Hyperactivity
• Rapid Heart Rate
• Palpable Thyroid Gland

How is hyperthyroid disease diagnosed?

Fortunately feline hyperthyroidism is fairly easy to diagnose. On physical examination, a veterinarian may note: underweight patients, increased heart rate (sometimes with an abnormal rhythm), unkempt hair coat/appearance, and a palpable thyroid gland(s). Definitive diagnosis is done with blood work. An elevated T4 value on blood work indicates feline hyperthyroidism. Other diagnostic testing your veterinarian may recommend to rule out any concurrent diseases would be: CBC (Complete Blood Cell Count), Blood Chemistries, Urinalysis, Chest and/or abdominal radiographs, blood pressure and abdominal or cardiac ultrasounds.

How is hyperthyroidism treated?

Treatment for feline hyperthyroidism falls under two categories: medical MANAGEMENT and Treating or CURING the disease.

1. Medical Management

• Anti Thyroid Drug Therapy
• Iodine Restrictive Diet

2. Treating or CURING Hyperthyroidism

• I-131 or Radio Iodine Therapy
• Surgery.

Please click on our “Treatment Options” section for more detail on treatment options.

What is the prognosis of a hyperthyroid cat?

Cats diagnosed with hyperthyroidism generally have a good prognosis WHEN TREATED. Factors to consider would be any concurrent disease processes your cat may also have been diagnosed with. Most cats respond well to treatment, especially Radio Iodine- which is successful in CURING hyperthyroidism 98% of the time. Left untreated, the disease will progress and shorten the life span and decrease the quality of life of the cat.