Hypothyroidism, or lack of sufficient thyroid hormone in the body, has so many symptoms that you're probably relieved when your dog has a definite diagnosis. Although it's not curable, the condition usually responds to daily synthetic thyroid supplementation. Giving your dog thyroid pills isn't going to make a difference overnight. It could take two or more months before you notice the medication's effect on your dog.
Since the thyroid glands regulate so much of the body's metabolism, when they are out of whack all kinds of things can go wrong with your dog. Symptoms include weight gain, behavioral changes, hair loss, frequent infections, cold intolerance, lethargy, dull coat, smelly skin, reproductive problems, constipation, eye issues, slow heart rate and anemia. Your vet diagnoses hypothyroidism via a blood test, measuring the level of thyroid hormone circulating in the blood.
Once your dog is on medication, you must bring him to the vet for frequent monitoring. It's important that your dog receives the correct dosage of thyroid medication, which is initially based on the animal's weight. Your dog requires testing, including a complete blood panel, at least twice a year.