Dog Thyroid Medication Side Effects

If your vet diagnoses your pet with a dog thyroid problem, you'll need to take prompt action in order to ensure that your pet is adequately cared for. Thyroid conditions can lead to a variety of damaging and potentially fatal conditions in and of themselves, not to mention that the symptoms of such a condition might be quite devastating to your pet's way of life.

Before you give your pet any number of different synthetic thyroid hormones, like Thyroxin, or other treatment methods and supplements, however, it's crucial that you work with your vet to understand all of the potential side effects.

In some cases, it will actually make more sense to limit the medication that your dog will receive, particularly if the side effects of that drug are such that they may cause issues for your pet worse than those that his thyroid condition will bring about. Some of the most common side effects of dog thyroid medication include the following.

Excessive Thirst and Hunger

One of the more common side effects of many different types of thyroid medication is thirst and hunger. Your pet may find himself unable to properly gauge when he is sated or when he's thirsty, and the result is often that he'll continue to eat and drink as long as there is food in front of him. While in many cases this may just be an annoyance to you, as your pet may continue to beg and whine for food, it can also be an important and dangerous side effect. If you provide your dog with too much water or food, he's likely to throw up. This can also cause him to eat foods outside that he shouldn't get in to.

Sensitivity to Heat

Dogs on thyroid medications are oftentimes especially sensitive to heat. This is important to keep in mind if you live in a warmer area or if your pet is on one of these medicines over the summer. Be sure to give your pet ample water and time int he shade when you're outside, and don't push him too hard if he has a thyroid condition.


Many thyroid medicines cause hyperactivity in a wide variety of dogs. These dogs are often prone to hyperactivity anyway, but the medicine itself will bring it about more frequently. Watch out for pets that run and jump around the house and get overly aggressive. Try to not work your dog up by feeding into this behavior at all, and strive to keep your pet's environment as calm and quiet as possible.

Temperament Changes

One of the most frustrating things about thyroid medication is that it can affect the way that your pet behaves in a general way. While this may not pose any problems to his health, it can still be unusual to see your pet suddenly acting quieter or louder, more or less aggressive than he normally is, or to notice some other change in his behavior.

If you notice these or any other symptoms of a thyroid medicine side effect, take your pet to the vet for an examination right away.