Hypothroidism causes a wide variety of symptoms but is often suspected in dogs that have trouble with weight gain or obesity and suffer from hair loss and skin problems. Hypothyroidism is easy to diagnose with a blood test that checks the level of various thyroid hormones including T3 and T4. Most hypothyroid dogs respond readily to treatment with synthetic thyroid medication such as Soloxine. Many dogs suffer from a low thyroid hormone level for years without treatment. If your dog has chronic recurrent skin problems, she may be suffering from hypothyroidism.
Hypothyroidism results from the impaired production and secretion of thyroid hormone.
The production of thyroid hormone is influenced by the pituitary gland, the hypothalamus and the thyroid gland. About half of the causes of thyroid gland destruction are suspected to be caused by the dog's own immune system killing the cells of the thyroid gland. The other half is caused by atrophy of the thyroid tissue and resultant infiltration of the tissue by fat. The cause for this form of the disease is unknown. Although the onset of clinical signs is variable, hypothyroidism most commonly develops in middle-aged dogs between the ages of 4 to 10 years.