Hyperthyroidism Common in Older Cats

Feline hyperthyroidism affects more than 10 percent of cats over age 10 and is now the most common endocrine disease of cats.

Cats given canned food are two to five times more likely to develop hyperthyroidism than cats that eat dry food. Zhuravlev Andrey/Shutterstock

Q: Our senior cat is hyperthyroid. How common is hyperthyroidism, and what causes it?

A: Hyperthyroidism is caused by benign tumors in the two thyroid glands located in the cat’s neck. The tumors produce excessive thyroid hormone, which impacts all body systems.