Optimal treatment requires a combination of home and professional veterinary care. At home it is important to administer all medication exactly as prescribed by your veterinarian.

With appropriate therapy, most of the clinical alterations associated with primary hypothyroidism are reversible. Generally, an improvement in attitude and activity are seen within a couple of weeks, and hair coat and skin changes improve within four to six weeks of the initiation of therapy.

Most dogs tolerate thyroid supplementation very well; however, overdosage is associated with signs of hyperthyroidism. Watch the dog closely for signs of anxiety, hyperactivity, pacing and restlessness, excessive drinking and/or urination, weight loss and diarrhea, and report these signs to your veterinarian promptly.

It is important to follow-up with regularly scheduled visits to your veterinarian so that both your dog's clinical signs and thyroid concentration in the blood can be monitored. Generally, the first follow-up examination is four to eight weeks after the start of therapy. T4 levels are often measured four to six hours after the morning pill is given or just prior to the evening pill. Adjustments in the dosage of medication are then recommended depending upon the results of these tests. Additional recheck visits are then scheduled based upon the test results, changes in clinical signs, and any alterations in the medication schedule.

Periodically throughout the dog's life, repeated measurement of T4 are necessary to ensure that the hypothyroidism remains well controlled. Additional testing depends on the clinical course of the illness.

The prognosis for reversal and control of primary hypothyroidism is very good. Hypothyroidism associated with disorders of the hypothalamus and pituitary gland, as well as tumors of the thyroid gland, has a poorer prognosis.