Hyperthyroidism in cats is a common endocrine disorder caused by an overproduction of thyroid hormones, usually due to a benign tumor on the thyroid gland. This condition often affects older cats and can lead to symptoms such as increased appetite, weight loss, hyperactivity, and excessive thirst. Diagnosis typically involves blood tests to measure hormone levels, and treatment options include medication, radioactive iodine therapy, or surgery. Managing hyperthyroidism is essential to prevent complications, such as heart disease and high blood pressure, ensuring a better quality of life for affected cats.