Cat Hyperthyroidism Recognition and Treatment Options

Hyperthyroidism is the most common endocrine disorder in older cats, causing weight loss, hyperactivity and cardiac changes. Multiple effective treatment options exist with different welfare profiles.

Key Facts

Hyperthyroidism affects approximately 10% of cats over 10 years and is caused by a benign thyroid adenoma in most cases
Classic signs include weight loss despite increased appetite, hyperactivity, vomiting and poor coat condition
Treatment options include daily medication (methimazole), radioiodine (I-131), surgery and dietary iodine restriction
Radioiodine is curative in over 95% of cases with a single treatment and is considered gold standard
Masking concurrent kidney disease is an important consideration when starting any treatment

Welfare Considerations

Untreated hyperthyroidism causes progressive weight loss, cardiovascular damage, hypertension and chronic discomfort. The hyperactive metabolic state is not a happy one despite the apparent energy increase. Treatment significantly improves quality of life for most cats. The choice between treatment options involves welfare trade-offs including daily medication stress versus radioiodine isolation.

What You Can Do

Schedule veterinary health checks including thyroid palpation and T4 measurement annually for cats over 8
Seek prompt treatment if hyperthyroidism is diagnosed to prevent cardiac and renal complications
Discuss all treatment options including radioiodine with your vet to choose the most welfare-appropriate approach
Monitor for hypertension complications including retinal detachment requiring emergency treatment
Reassess kidney function 4-6 weeks after treatment begins as CKD may be unmasked