Canines rarely suffer from hyperthyroidism, or too much thyroid hormone in their system. Instead, hypothyroidism, or lack of sufficient hormone, is much more common. If your dog is diagnosed with hypothyroidism, your veterinarian likely will prescribe thyroid medication that your pet must take for the rest of his life. Never stop giving your dog this medication without your vet's approval. Marketed under various trade names, levothyroxine sodium is often prescribed for canine hypothyroidism treatment.
Dogs with low thyroid levels usually suffer from skin infections, hair loss, lethargy, obesity and poor coat quality. When given medication, these conditions often improve fairly quickly. If a dog no longer receives thyroid medication, these symptoms will recur within weeks, but the most obvious and immediate side effects concern behavioral changes. Your normally good-natured dog might quickly become irritable and agitated. Stopping the drug probably won't kill your dog, but it will adversely impact his health. If your vet suspects your dog was misdiagnosed and is not hypothyroid, your dog can't receive medication for two months to ensure blood test accuracy. Dogs diagnosed with hyperthyroidism almost always have thyroid cancer, so surgery is the primary treatment and the prognosis is usually poor.
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