Hypothyroidism is a disease caused low thyroid production by the thyroid gland. The thyroid hormones regulate the metabolism and affect many organs. Hypothyroidism is a common disease in dogs, but rare in cats. The condition can result from any disease that damages the thyroid gland or the central brain mechanism that controls the thyroid gland.
There are two kinds of the disease:
Primary hypothyroidism occurs when the disease affects the thyroid gland itself. Possible causes are inflammation, atrophy, iodine deficiency, infection, or cancer.
Secondary hypothyroidism occurs when the disease affects the brain and the control of the thyroid gland. Possible causes are cancer, infection, or deformity.
A temporary low thyroid hormone level can occur due to
malnutrition, concurrent illnesses, or steroid therapy.
In practice the cause of the disease is often unknown.
Signs develop gradually and they may include lethargy, fatigue, depression, weight gain and reduce activity. The skin will often show symmetrical areas of hair loss starting at the tail and might develop infections. Other signs that sometimes occurred are neurological deficit and constipation.
Diagnosis is maid by history, physical exam and blood tests. Often several blood tests are done over a period of time.
Treatment consists of lifetime thyroid hormone supplement. Regular check-ups and blood tests, which include Thyroid hormone level are needed. Low fat diet and medication for skin conditions are often warranted.
The prognosis for animals with primary hypothyroidism is good, if they are treated. Dogs with secondary hypothyroidism have guarded to poor prognosis, as part of the brain is involved.[Back]