Hypothyroidism in Dogs

Hypothyroidism in Dogs

                Last week we discussed hyperthyroidism in cats.  Dogs have the opposite problem which is hypothyroidism or low amounts of circulating thyroid hormone.  The thyroid gland produces hormones which help to control metabolism, speeding up or slowing down body functions.  Hypothyroidism is a decrease in the production of thyroid hormone.

                What causes hypothyroidism?  Atrophy of the thyroid gland caused by aging or by destruction of the gland by the patient’s own immune system are the most common causes of hypothyroidism in dogs.  Dogs with hypothyroidism are typically middle-aged or older dogs and breeds like Dobermans, Golden Retrievers, and Boxers and Dachshunds have a higher incidence of thyroid disease.  Symptoms include unexplained weight gain or failure to lose weight, dull, dry skin and hair coat and lethargy or decreased activity.

                Hypothyroidism is diagnosed by checking blood levels of thyroid hormones known as T4 and free T4.   In many dogs, the T4 levels can be falsely lowered by other illnesses or by certain medications and dogs like greyhounds have T4 levels that are lower than other breeds, so, a hormone called free T4 (meaning it is not bound to other proteins in the blood) needs to be measured to accurately diagnose hypothyroidism.  Some patients may be difficult to diagnose and may require additional blood tests checking levels of TSH (thyroid stimulating hormone) or other thyroid-associated hormones.

                Treatment is fairly straight forward:  dogs need to take a synthetic thyroid hormone supplement.  Thyroid supplements will normalize the thyroid hormone levels and control symptoms of thyroid disease, but do not cure the disease, so, medication is needed for the rest of the dog’s life. 

                Any dog, especially high risk breeds, who are obese, lethargic or have chronic skin problems should be screened for hypothyroidism.  Treatment can dramatically improve quality of life.

                This blog brought to you by the Patton Veterinary Hospital serving Red Lion, York and the surrounding communities.