As long as you continue to treat your dog’s hypothyroidism with the guidance of your vet, your pup should be able to live a long and happy life with a normal life expectancy. Once your vet diagnoses hypothyroidism in your dog, they will recommend a thyroid medication for dogs. This is usually a form of synthetic thyroid hormone your dog will have to take for the rest of their lives. You will also likely need to take your dog to the vet twice a year for testing. Your dog’s thyroid levels can change over time, and your vet may need to update your pup’s prescription to make sure they receive the right levels of synthetic thyroid hormones.