Hypothyroidism in Dogs: What’s the Skinny?

(Photo by Matthew Pilachowski)

A Note From Dr. John:

Have you ever wondered why your dog does not eat that much yet continues to gain weight? Do you find yourself wondering how in the world his energy can be THAT low? Is Fluffy not so fluffy anymore? Or does she have persistent ear and skin infections?

If you’ve tried to address the more common causes of these issues such as overfeeding, inadequate grooming, and allergies with no success, your furry friend might be hypothyroid.

What is hypothyroidism?
The thyroid gland produces your pet’s thyroid hormone which regulates his or her metabolic rate.  Hypothyroidism is a condition in which the thyroid gland does not produce enough of the thyroid hormone.  Decreased hormone levels lead to low energy, weight gain, poor coat, and skin infections.  Elevated hormone levels, on the other hand, lead to high heart rate and blood pressure- a condition known as hyperthyroidism.

How did my dog become hypothyroid?
Hypothyroidism has several causes: immune-mediated destruction of the gland, natural gland atrophy over time, dietary iodine deficiency, and congenital hypothyroidism.  The first two causes account for the vast majority of the disease within the general dog population. The last two are rarely encountered in veterinary medicine. 

We should note that certain breeds are more predisposed to the disease.  These breeds are Doberman Pinschers, Golden Retrievers, Irish Setters, Great Danes, Dachshunds, and Boxers.

How do I know if my dog has hypothyroidism?
Blood work performed by your veterinarian is necessary to diagnose hypothyroidism. Usually these results are pretty straight forward, though sometimes your pet may fall into a bit of a gray zone based on his or her lab results. Regardless, your veterinarian should be able to walk you through this process.

So my dog is hypothyroid- what’s next?
The bad news is that hypothyroidism is a lifelong condition. The good news is that hypothyroidism is treatable with a relatively cheap and easy to administer medication that is given twice daily. The even better news is that treatment typically results in dramatic improvement in your dog’s health. Many dogs regain that puppy energy from years ago, and the not-so-fluffy Fluffy often regrows that healthy coat that may have been missing for quite some time. In addition, extra pounds tend to melt away- sometimes effortlessly! 

What about follow up?
Once your dog has started a thyroid supplement, you should have the thyroid blood levels rechecked about 2 months after the initial diagnosis. Since hypothyroidism is a lifelong disease, regular yearly blood level checks are recommended as well.

Our information is not intended to replace the advice of your veterinarian.  Do not use this information for diagnostic purposes. Always take your pet to your veterinarian to obtain a diagnosis and course of treatment.