Hypothyroidism is a relatively common problem in both aging people (women) and dogs (we almost never see a hypothyroid cat!). It is a condition where the thyroid gland/activity can no longer maintain normal levels of circulating thyroid hormones. These hormones are important in setting the metabolic rate or function of all cells within the body.
Cause: In most cases hypothyroidism is a result of a gradual atrophy or shrinking of the gland. In some cases, the thyroid gland cells are attacked by the immune system, an autoimmune process resulting in a condition called lymphocytic thryoiditis.
Susceptibility: This condition is most commonly diagnosed in dogs between the ages of 4 to 10 years of age. Breeds that have an increased risk for hypothyroidism include: Afghan, Airedale, Boxer, Shar pei, Chow, Cocker Spaniel, Dachshund, Doberman, Bull dog, Golden Retriever, Great Dane, Irish Setter and Miniature Schnauzer.
Clinical Signs: Like most diseases not all animals exhibit the same signs. Many of the common signs involve changes in hair coat. Dogs may show a poorer (dry or greasy) hair coat, slower hair re-growth and in severely affected animals, areas of symmetrical hair loss with or without skin darkening (pigmentation).
Many hypothyroid dogs gain weight easily and sometimes have decreased energy levels. Other signs may include slower heart rates, lethargy, intolerance to cold, infertility, constipation and rarely seizures.
Diagnosis: Hypothyroidism is easily diagnosed through a blood test looking specifically at hormone levels called T4 and TSH.
Treatment: This condition is easily and inexpensively treated with lifelong thyroid hormone supplementation. In most cases we prescribe the human medication Synthroid, to your local drugstore. We do not want to over supplement with this medication so we must check your dogs T4 level (generally once yearly) while on the drug. Giving too much thyroid hormone creates a condition known as hyperthyroidism which can be deadly if left unchecked.