Cat Hyperthyroidism: Managing a Common Feline Disease

Hyperthyroidism is the most common hormonal disorder in older cats, causing a range of distressing symptoms if untreated, but responding well to several effective treatments.

Key Facts

Hyperthyroidism affects approximately 10% of cats over age 10
Caused by benign tumors of the thyroid gland in 98% of cases
Symptoms include weight loss despite increased appetite, hyperactivity, and vomiting
Four treatment options exist: medication, radioactive iodine, surgery, and prescription diet
Radioactive iodine is considered the gold standard and is curative
Untreated hyperthyroidism causes heart disease and kidney problems

Welfare Considerations

Hyperthyroid cats experience a state of metabolic overdrive that causes distressing hyperactivity, inability to rest comfortably, muscle wasting, and rapid weight loss despite ravenous hunger. The condition feels similar to severe anxiety and physical exhaustion simultaneously. Without treatment, the excessive thyroid hormone causes permanent heart damage and hypertension. With treatment, most cats experience dramatic improvement in comfort and quality of life within weeks.

What You Can Do

Schedule a thyroid screening for cats over age 10 as part of annual exams
Recognize early signs: weight loss with good appetite, increased vocalization, restlessness
Discuss treatment options with your vet to find the best approach for your cat
Monitor treated cats for hypothyroidism as kidney disease may become apparent after treatment
Consider radioactive iodine treatment as a curative option if available in your area