Often the cat has a pinched look to its expression. These cats are usually very active and are often described as restless. Weight loss can be marked even though eating well. On examination a thyroid nodule may be palpable in the region of the ventral neck. The heart rate is usually elevated and murmurs are often detected.
Blood tests reveal elevated thyroid hormone level and often elevated liver enzymes.
Hyperthyroidism is due to an overactive thyroid producing excess amounts of thyroid hormone. This excess leads to an increase in metabolism. This results in weight loss, an elevated heart rate and often an increase in blood pressure. These cardiovascular changes can lead to anatomical changes in the heart itself. Treatment is aimed at lowering the circulating levels of thyroid hormone.