Hypothyroidism
Hypothyroidism is one of the most common endocrine diseases seen in dogs. It is extremely rare in cats and is usually due to treatment for hyperthyroidism. It is more common in medium-to large-sized dogs and many breeds are predisposed.
Hypothyroidism is most commonly caused by circulating antibodies to the thyroid gland. This is considered an immune-mediated disease. There is no genetic link, but Golden retrievers, Labradors, dachshunds, boxers, and Cocker spaniels are predisposed.
Most owners first notice their pet becoming lethargic or gaining weight. They will usually attribute this to aging. These pets will also have a poor hair coat, and their hair may actually start to fall out, especially on the trunk and tail. Many pets will be groomed or otherwise shaved and the hair will never grow back, or grow back a different color. Patients will recurrent skin or ear infections should have their thyroid checked.
Treatment is extremely simple and cost-effective. All pets will require thyroid supplementation for life, usually twice daily. Blood work should be routinely monitored to assess need to increase or decrease the dose. These pets generally have an excellent prognosis and life expectancy is normal.
