Hyperthyroidism is the most common hormonal disease of older cats. Early diagnosis and appropriate treatment significantly improve quality of life for affected animals.
Hyperthyroid cats experience significant welfare impacts that owners may initially misattribute to normal aging. The elevated metabolism causes anxiety, restlessness, vocalization (especially at night), and difficulty settling. Concurrent hypertension can cause retinal detachment and sudden blindness. Heart disease from untreated hyperthyroidism is progressive and eventually fatal. A cat experiencing all these effects simultaneously - anxiety, chronic hunger despite eating, weight loss, heart disease - has significantly reduced quality of life. The good news is that treatment is highly effective: radioactive iodine treatment cures the condition permanently with minimal discomfort, restoring normal metabolism and resolving associated cardiac and neurological effects.