low level of thyroid hormone.

Not enough thyroid hormone in the blood-lowered activity of thyroid gland. Lack of thyroid hormone appears as slowing down of all bodily processes. Condition caused by deficiency of thyroid hormone.

Deficiency of thyroid hormone which is normally made by the thyroid gland which is located in the front of the neck. Hypothyroidism can result in hair loss.

decreased production of thyroxine, causing poor coat, weight gain, mental dullness, fatigue, cold intolerance, and infertility.

See Hypothyroidism.