Cat Senior Hyperthyroidism: Managing a Common but Demanding Condition

Hyperthyroidism is the most common hormonal disorder in older cats, causing significant metabolic disturbance. Early diagnosis and treatment preserve quality and length of life.

Key Facts

Hyperthyroidism affects approximately 10% of cats over 10 years of age
It is caused by a benign tumour of the thyroid gland producing excess thyroid hormone
Signs include weight loss despite good appetite, increased vocalisation, restlessness, vomiting, and a poor coat
Left untreated it causes heart disease, hypertension, and kidney damage
Treatment options include daily medication, radioactive iodine (curative), surgery, or dietary management
Radioactive iodine is considered the gold standard treatment with high cure rates

Welfare Considerations

Hyperthyroidism causes significant welfare impact through weight loss, cardiovascular stress, hypertension, and the anxiety-like state associated with excess thyroid hormone. Many cats appear ravenous yet lose condition, which represents a distressing metabolic imbalance. Treatment significantly improves quality of life — cats typically calm down, regain weight, and show improved coat condition. However, treating hyperthyroidism can unmask underlying kidney disease, requiring careful monitoring post-treatment to reassess overall kidney function.

What You Can Do

Schedule annual health checks for cats over 8 years, including thyroid palpation and blood tests
Do not delay seeking veterinary advice if your older cat is losing weight despite eating well
Ask your vet about all treatment options and their suitability for your cat's lifestyle
Monitor blood pressure in hyperthyroid cats — hypertension can cause blindness and stroke
Join a pet health support group if managing a cat with chronic hyperthyroidism