Cat Senior Wellness: Hyperthyroidism Screening

Regular screening for hyperthyroidism in senior cats enables early diagnosis before the condition causes significant welfare harm, allowing timely treatment with excellent outcomes.

Key Facts

Hyperthyroidism is the most common endocrine disease of cats, primarily affecting those over 10 years
An estimated 10% of cats over 10 years have hyperthyroidism, rising to higher proportions at older ages
Early signs include increased appetite and vocalisation, weight loss, and restlessness — often misattributed to normal ageing
Total T4 blood testing is the primary screening test and should be included in routine senior cat wellness panels
Treatment options include medication, radioactive iodine, and surgery — all highly effective when initiated early

Welfare Considerations

Hyperthyroidism causes significant welfare harm through its systemic effects: weight loss despite increased appetite, hypertension causing retinal detachment and blindness, cardiac disease from chronically elevated heart rate, and the restlessness and anxiety associated with thyrotoxicosis. Many cats suffer for months before diagnosis as signs are attributed to normal ageing. Routine senior screening including thyroid hormone testing detects the condition at an early, more easily treated stage. Treatment is highly effective — radioactive iodine cures the condition in 95-98% of cases — making hyperthyroidism one of the most treatable chronic diseases of senior cats when diagnosed before significant secondary organ damage occurs.

What You Can Do

Include total T4 measurement in routine blood panels for cats over 8-10 years at least annually
Investigate weight loss despite good appetite in senior cats urgently rather than attributing it to ageing
Discuss treatment options including radioactive iodine with your veterinarian if hyperthyroidism is diagnosed
Monitor blood pressure in hyperthyroid cats as hypertension can cause blindness requiring concurrent treatment