Hypothyroidism is an extremely common disease found most often in dogs over the age of six. Golden Retrievers, Labrador Retrievers, Irish Setters, Dobermans and other medium to large sized dogs are most commonly affected. The thyroid gland is located in the neck of your dog on either side of the trachea. It is controlled by the pituitary gland which is located in the brain. In cases of hypothyroidism the thyroid gland is underactive and does not produce enough thyroid hormone. This decrease in thyroid hormone causes the metabolic rate to slow. Inflammation or shrinkage of the thyroid gland is usually responsible for the decrease in thyroid hormone production.
Symptoms of hypothyroidism can include weight gain, lethargy, cold intolerance, dry or dull haircoat, baldness, changes in the pigmentation of the skin, and repeat skin or ear infections. Several other conditions can be associated with hypothyroidism including KCS (dry eye), corneal ulcers, deafness, anemia, chronic constipation, thickening of the skin on the face, increased aggression, nerve paralysis, ataxia, and infertility.
Diagnosing hypothyroidism is done with a blood test. The primary hormone produced by the thyroid gland is called thyroxin. A blood test called a T4 tests the level of thyroxin in the blood. The T4 test is included in our routine blood work that is sent off to the lab. Aside from a T4 it is also important to perform full blood work including a Complete Blood Count and Chemistry whenever possible when trying to diagnose hypothyroidism. Before beginning treatment for hypothyroidism it is important to ensure that all other organ systems are functioning properly.
Hypothyroidism is easily treated with a medication called Soloxine. Soloxine is a thyroid replacement hormone that comes in pill form. It must be given twice daily for the rest of the dog’s life. The initial dosage of Soloxine should be given for 30 days and then a T4 should be rechecked in the clinic. Further adjustments may be necessary and the T4 should be tested every 30 days until the thyroxin levels fall within the recommended range. Blood for a T4 test must be drawn 4-6 hours after your pet’s morning dose of medication. Once the correct dosage of Soloxine has been determined a T4 should be performed every 6 months. As dogs age the dosage may need periodic adjustment, so these semi-annual tests are extremely important in order to ensure that your dog continues to get the best treatment possible.
Successful treatment of hypothyroidism should result in the reversal of the majority of symptoms associated with the condition.