Many of our feline companions will become diagnosed with hyperthyroidism as they enter their senior years. While this disease process takes quite a bit of effort from the owner, and compliance from our furry friends, it is manageable long term!

What is hyperthyroidism?

Hyperthyroidism is an endocrine disease in which the thyroid gland overproduces the thyroid hormones thyroxine and triiodothyronine. The overproduction of these hormones leads to an increased metabolic rate which leads to subsequent weight loss over time. It is a common misconception that older cats become thin solely due to their age, but there is usually cause for the weight loss – and, more often than not, there are ways we can manage it!

How is it diagnosed?

During a physical examination, the veterinarian may notice an increased heart rate, a heart murmur, an enlarged thyroid gland, or high blood pressure. Many patients will show signs of being hyperthyroid which are most commonly weight loss, increased hunger, increased thirst, increased activity levels, vomiting, and diarrhea. These signs and symptoms are all directly related to the increase in their metabolic rate due to the rise in hormones. The only way to truly diagnose hyperthyroidism is to measure the levels of thyroid hormones in the blood. An increased level is indicative of being hyperthyroid. A simple blood check is all it takes for the veterinarian to start to get your kitty back on the right track!

How is it treated?

The most common form of treatment is by the administration of a medication called Methimazole. This medication comes in multiple forms to allow for easy administration to our furry friends – liquid, pills, and a transdermal gel, allowing for absorption through the skin. Through careful aid from the veterinarian, a dose can be prescribed to begin controlling the hormones. As Methimazole works by blocking the synthesis of thyroid hormone, subsequent rechecks of the thyroid levels must be repeated every 3-4 weeks following a dose change, until a suitable dose is found to control the hormone levels.

Other forms of treatment may include surgically removing the thyroid gland (thyroidectomy), or through a radioactive iodine treatment which will be absorbed into any abnormal thyroid tissue, destroying it. These treatment options are more permanent than treating with medications and are done at specialty hospitals.

Most cats are diagnosed with hyperthyroidism during their senior years, so now is a very good time to have your loved ones checked! October and November are our Senior Focus months at Coxwell Animal Clinic, so be sure to book an appointment for discounted blood work!

– McCurnin’s Clinical Textbook for Veterinary Technicians, Eighth Ed.

Written by: Claire Pethick, RVT