Two thyroid tumors from an 18-year-old domestic shorthaired cat with severe, long-standing hyperthyroidism. In normal cats, the thyroid gland consists of two separate lobes or parts, each of which measures approximately 1-cm in length and 0.25-cm in width. As you can see, both of this hyperthyroid cat's thyroid tumors were 5-10 times that of normal size.