elevated level of thyroid hormone, the hormone that regulates metabolism.

excessive production of thyroid hormones, often seen in older dogs, causing excessive thirst, weight loss, increased appetite and restlessness.

Excess of thyroid hormone resulting from an overactive thyroid gland (or taking too much thyroid hormone). Symptoms can include increased heart rate, weight loss, depression , and cognitive slowing. Treatment is by medication, the use of radioactive iodine, thyroid surgery, or reducing the dose of thyroid hormone. See the entire definition of Hyperthyroid