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Muscle Atrophy in Cats: What Causes It?

Dr. Mark is a veterinarian with over 40 years of experience in the field. He works with dogs, cats, exotics, and livestock.

Hypothyroidism is the most common cause of muscle atrophy in felines.

Hypothyroidism is the most common cause of muscle atrophy in felines.

Why Do Cats Get Muscle Atrophy?

It is common to see excessively thin older cats suffering from kidney disease and diabetes, but the most common cause of muscular atrophy most of us see is hyperthyroidism.

Hyperthyroidism in Cats

Hypothyroidism is an endocrine disease in which the pet's thyroid puts out more thyroid hormone than the cat needs, and almost 75% of all cats with this disease suffer from muscle atrophy. (1)

Even after treatment, about half of cats with hyperthyroidism never regain their muscle mass and still look thin and wasted. If not treated, however, the heart muscle will also waste away and the cat will die.

Take Your Cat to the Vet for an Examination

Hyperthyroidism needs to be diagnosed with blood testing so if your cat has muscular atrophy for any reason, be sure to take him in for an examination and testing.


  1. Peterson, M. E., Castellano, C. A., & Rishniw, M. (2016). Evaluation of Body Weight, Body Condition, and Muscle Condition in Cats with Hyperthyroidism. Journal of veterinary internal medicine, 30(6), 1780–1789.

This article is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from your veterinarian. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.

© 2022 Mark dos Anjos DVM