Hypothyroidism is caused by a decreased production of thyroid hormone. This condition occurs most commonly in older dogs and is rare in cats.

Signs of hypothyroidism include weight gain, lethargy, dull or poor hair coat and/or flaking skin.

Hypothyroidism is diagnosed by bloodwork to check thyroid function.

Treatment of hypothyroidism is administration of an oral hormone replacement for life. This medication is typically given twice daily initially then maintained on once daily dosing. Throughout treatment it is recommended that routine monitoring of thyroid levels be performed and medications adjusted as indicated.

The majority of patients treated return to normal and live a normal life.