Canine hyperthyroidism is a condition where a dog's thyroid gland produces excessive amounts of thyroid hormones. This can lead to symptoms such as increased appetite, weight loss, hyperactivity, and changes in behavior. It is less common in dogs than in cats, and when it occurs, it is often associated with thyroid tumors. Diagnosis typically involves blood tests to measure hormone levels, and treatment options may include medication, surgery, or radioactive iodine therapy. Regular veterinary check-ups are essential for managing this condition and ensuring the overall health of the dog.