Hyperthyroidism in Cats

What is the Thyroid Gland?

Located in the neck, this gland controls metabolism (energy use) for the entire body. Hyperthyroidism is when the thyroid gland overproduces hormone, increasing an individual’s metabolism and energy consumption.

What causes Hyperthyroidism?

This is a fairly common disease in older cats. The gland itself enlarges and production of thyroid hormone increases. The increased levels of hormone affect different body systems, most notably the heart – which can lead to high blood pressure and heart failure.

Signs your cat may have Hyperthyroidism

  • Middle-aged or older (average age is 12-years-old)
  • Weight loss
  • Normal to increased appetite
  • Drinking more water/frequent trips to the litter box
  • Vomiting / Diarrhoea
  • Not grooming/unkempt hair coat
  • Blindness

How do we diagnose Hypothyroidism?

A veterinarian will perform blood tests that will tell us if a cat has the disease.


Treatment is usually quite successful, and there are different options available. Most recently, a new prescription food has become available, and in some cases, cats with hyperthyroidism can be managed with a diet change only. Once diagnosed, a veterinarian will be able to discuss all treatments options with you, and together the best option can be chosen.

If your cat is showing any of the above signs, give us a call and book an appointment to have their thyroid gland checked today!

Written by Dr. Adam Mahovlich, DVM