Clinical Signs of Hyperthyroidism In Cats

Hyperthyroidism or excess thyroid hormone production is a common problem in older cats.  For unknown reasons,some cats develop tumors on their thyroid glands as they age.  Although the majority of these tumors are considered benign because they do not metastasize, that does not mean that they do not affect the cat.  Thyroid ademonas secrete large quantities of thyroid hormone, far more than what the cat needs.  The high level causes a host of effects all related to an increased metabolic rate.

Clinical signs of hyperthyroidism: 

1)   Tachycardia (increased heart rate usually over 200 bpm).
2)   Gallop rhythm.
3)   Weight loss even though the cat eats well.
4)   Increased activity.  People often tell me the cat is running around like a kitten.
5)   Diarrhea.
6)   Vomiting.
7)   Hypertension.
8)   A thyroid nodule felt on the cat’s neck. 
9)   Acute blindness caused by retinal detachment secondary to the hypertension.
10) Vocalization.  Cats meow in a long, drawn out fashion.

*In my experience, weight loss is the most common sign of hyperthyroidism.

Published by kristennelsondvm

Dr. Kristen Nelson grew up on a farm in Watertown, Minn., where she developed a deep love for animals of all kinds. She received a Doctor of Veterinary Medicine degree from the University of Minnesota, College of Veterinary Medicine. Kris then completed a small-animal internship at the prestigious Animal Medical Center in New York City. In addition to writing and speaking, she cares for small and exotic animals in Scottsdale, Az. Dr. Nelson is widely quoted in the media. Her credits include Ladies’ Home Journal, USA TODAY, the Los Angeles Times and numerous radio and television interviews. Dr. Nelson has written two books, Coated With Fur: A Vet’s Life and Coated With Fur: A Blind Cat’s Love. Kris and her husband Steve share their home with rescued cats, birds and a dog.