Hyperthyroidism: The Signs, Diagnosis, and Treatment

Signs, Symptoms, and Treatment of Hyperthyroidism Mount Carmel Animal Hospital

Hyperthyroidism is a medical term that means “overactive thyroid, and it’s prevalent in older cats.

Hyperthyroidism is a medical term that means “overactive thyroid.” In cats, it’s the most common glandular disorder. The cause of it is an excessive concentration and circulation of thyroxine, a thyroid hormone referred to as T4, in the bloodstream. Older cats more commonly experience hyperthyroidism, and today we will discuss the signs, diagnosis, and treatment of this condition. 

The Signs/Symptoms of Hyperthyroidism

Cats with hyperthyroidism develop various symptoms that may be subtle at first, but they become more severe over time as the disease progresses. These signs can include:

  • Weight Loss
  • Increased Appetite, Thirst, and Urination
  • Increased vocalization
  • Hyperactivity
  • Vomiting
  • Diarrhea
  • An unkempt or matted coat


As part of a regular physical examination, one of our veterinarians will palpate (examine by touch) your cat’s neck region to check for an enlarged thyroid gland. Our vet will also check your cat’s heart rate and blood pressure. If there is a possibility of thyroid disease, we will order a blood panel and analyze thyroid hormone levels. Felines who have hyperthyroidism will typically have elevated levels of T4. A small percentage of cats with an overactive thyroid gland do have normal T4 levels. If this is true for your feline friend, we can perform additional tests. 


The three proven treatments for hyperthyroidism include lifelong medication, radioactive iodine therapy, and surgery. The treatment a cat receives will depend on particular factors such as the patient’s overall health status, the owner’s ability to medicate the cat regularly, and financial considerations. Here is a summary of how these different treatments work. 

  1. Medication: Anti-thyroid drugs work by reducing the production and release of the thyroid hormone in the thyroid gland. This treatment is not a cure and requires you to medicate your cat for the rest of his/her life.
  2. Radioactive Iodine Therapy: Radioactive iodine comes in the form of an injection, and the bloodstream absorbs it quickly and removes the abnormal thyroid tissue without damaging surrounding tissues or parathyroid glands. This requires a trip to a specialty practice where your cat will stay in the hospital throughout treatment.
  3. Surgery: Surgical thyroidectomy or removal of the thyroid glands is a straightforward process with a high success rate, like radioactive iodine therapy. 

If you discover your feline friend experiencing any of these signs, call to schedule an appointment with one of our veterinarians today. For more information on cat health, keep checking out our weekly content. 

Here at Mount Carmel Animal Hospital, We’ll Treat Your Pets Like Family!

Mount Carmel Animal Hospital has been serving the Northern Baltimore/Southern York community for over 30 years and is proud to be an independently operated, small animal practice committed to excellence in veterinary medicine and client service. From grooming to wellness services, along with Canine Life Skills Training Courses, and surgical procedures, we have the expertise that will best serve the needs of you and your pet. Contact us at 410-343-0200 and follow us on Facebook!

This entry was posted on Friday, July 16th, 2021 at 2:45 pm. Both comments and pings are currently closed.