Cat Hyperthyroidism Welfare | Animal Welfare Hub

Hyperthyroidism is the most common hormonal disorder of older cats, causing significant welfare harm if untreated but responding well to management.

Key Facts

Feline hyperthyroidism affects approximately 10% of cats over ten years of age
It is caused by a benign tumour of the thyroid gland producing excess thyroid hormone
Signs include weight loss despite increased appetite, increased thirst, vomiting and behavioural changes
Untreated hyperthyroidism causes progressive muscle wasting and cardiac complications
Radioiodine therapy is the gold-standard curative treatment with high success rates
Daily oral medication with methimazole or carbimazole is effective but requires lifelong administration
Diet-based iodine restriction is an alternative management option

Welfare Considerations

Feline hyperthyroidism causes significant suffering including weight loss, cardiovascular strain and associated hypertension that can damage eyes and kidneys. The good news is that treatment is highly effective and quality of life post-treatment is excellent. The welfare challenge is early recognition - weight loss in cats is often dismissed as normal ageing when it reflects serious treatable disease. Senior blood testing that detects thyroid hormone elevation enables early intervention.

What You Can Do

Include thyroid hormone testing in annual blood panels for cats over ten years old
Seek veterinary attention for any unexplained weight loss in cats, even if appetite is maintained
Discuss all treatment options including radioiodine, medication and diet with your vet
Monitor treated hyperthyroid cats for recurrence with regular thyroid hormone checks