Hyperthyroidism is the most common endocrine disease of older cats. Multiple treatment options exist, each with different welfare implications, and the condition is highly manageable when treated appropriately.
Hyperthyroid cats experience persistent discomfort from elevated metabolism including restlessness, muscle wasting, and cardiovascular strain. Treatment dramatically improves quality of life. Radioactive iodine is the gold standard and eliminates the need for daily medication, reducing stress for cats who resist pilling. For cats treated with methimazole, monitoring for side effects including facial scratching and bone marrow suppression is essential. Regular thyroid level checks enable dose adjustment to maintain optimal health.