What You Need To Know About Hyperthyroidism In Cats

Hyperthyroidism in cats (also called feline hyperthyroidism) is a fairly common disease, and one that all cat owners should be aware of.

The disease is the result of excessive levels of the thyroid hormone, known as T4, produced by a growth or tumor on the thyroid gland. Although the growth itself is usually benign, the damage to an animal’s body that can result are often life threatening.

Feline hyperthyroidism most often affects middle-aged and senior cats. Learning how to recognize and treat this disease is key to keeping your kitty’s good health going long into his or her golden years.

Systemic Problems

Because thyroid hormones affect nearly organ in the body, hyperthyroidism can cause widespread secondary health concerns. Increased metabolism, heart rate, and blood pressure caused by hyperthyroidism can have deleterious effects on the heart, kidneys, eyes, and brain.

Spotting Hyperthyroidism In Cats

The symptoms of hyperthyroidism in cats can be similar to other disorders, such as diabetes, kidney failure, and even intestinal cancer. A thorough examination by your veterinarian is essential for the accurate diagnosis of feline hyperthyroidism.

Bring your pet in to see us right away if he or she is exhibiting any of the following symptoms:

  • Weight loss
  • Increased appetite
  • Increased water consumption
  • Increased urination
  • Vomiting/diarrhea
  • Behavior changes such as hyperactivity, aggression, vocalization

Screening for hyperthyroidism is routine for older cats, all the more reason to keep up with kitty’s regularly scheduled wellness examinations!


There are a variety of treatment options available for hyperthyroidism in cats. Your veterinarian will work with you to determine the best option for your cat.

  • Medication – Hyperthyroidism can usually be controlled through the administration of antithyroid medication called methimazole. The medicine can either be taken orally or applied topically, and must be administered throughout the lifetime of the cat.
  • Surgery – If your cat is healthy enough for surgery, removal of the thyroid gland can be an effective cure for hyperthyroidism.
  • Radioactive iodine treatment – Radioactive iodine treatment is expensive, and must be performed by a licensed facility, but it works. The injection of radioactive iodine is targeted directly to the thyroid, where it destroys the abnormal tissue responsible for the disease.
  • Diet – Strict adherence to a low-iodine prescription diet can be helpful in treating hyperthyroidism.

Depending on how advanced the hyperthyroidism has become, a cat may need additional treatment to address any secondary conditions that may have developed, such as hypertension or heart disease.

The long-term health and wellbeing of your cat is our top priority at Beverly Hills Veterinary Associates! Please don’t hesitate to contact us with any questions or concerns you may have regarding your pet.