In response to the question that was posted about thyroid diseases, here is a quick review of hypothyroidism in dogs.
Hypothyroidism occurs when the thyroid glands (the small glands located in the neck) do not produce enough thyroid hormone (thyroxine). This hormone is responsible for maintaining your dog's normal metabolism so too little thyroxine causes symptoms such as listlessness and weight gain. Other metabolic issues such as skin or haircoat problems, slow heart rate, and a lower than normal body temperature can also be seen in dogs with hypothyroidism.
Your veterinarian may suspect that your dog has hypothyroidism based on their symptoms but a true diagnosis will require measurement of the thyroid (T4) level in the blood. Sometimes, a low T4 level coupled with the symptoms is enough to make the diagnosis. If these results are not clear cut however, other tests such as a TSH level or a free T4 measured using a process called equilibrium dialysis may be required.
The good news is that this disease is easily treatable. You will need to give your dog thyroid hormone in the form of a pill that he will get once or twice a day for the rest of his life. Once your dog is on therapy, your veterinarian may recommend rechecking the thyroid level to be sure that the dose is correct. For dogs with hair loss, it may take 4 to 6 weeks before you start to see regrowth of hair. Increased activity is seen much sooner however at about 1 to 2 weeks after starting treatment.
If the signs listed above describe your pooch, call your veterinarian to schedule an appointment for blood testing.