Your dog’s thyroid gland is a neat little masterpiece that’s responsible for many functions. Among the thyroid gland’s functions one of the most important and well known is its ability in regulating the dog’s metabolism by producing thyroid hormones. Any disruption in this gland’s correct functioning may result in several complications that may affect a dog’s physical and mental well being. So today’s let’s learn more about a dog’s thyroid gland, where it’s located, its many functions, and some signs suggesting something may be wrong and require veterinary attention.
Introducing Your Dog’s Thyroid Gland
Hello, it’s your dog’s thyroid gland talking! Yes, I am quite a neat little masterpiece. I am a small gland consisting of two lobes that are found in your dog’s neck area, just underneath his voice box, also known as the larynx.
As my name implies, I am gland, which means that I produce special chemical substances, that are known as hormones. You see, I am composed of tens of thousands of follicles from which hormones are produced. What hormones do I produce? Thyroxine (T4) and tri-iodothyronine (T3) are produced by me and sent to your dog’s bloodstream.
A third hormone called TSH (thyroid stimulating hormone,) is produced by the pituitary gland found at the base of the dog’s brain. How much of this hormone is produced depends on how many thyroid hormones are in the bloodstream. Therefore, expect more TSH to be produced when the thyroid hormones I produce are are on the lower end.
Do you see the four little dark circles in the picture above? Those are parathyroid glands, little fellows that play an important role in maintaining optimal levels of blood calcium in dogs. These glands though deserve their own little story, so let’s move on to learning more facts about me and what I do.
I am The Boss of Metabolism
I am the boss of your dog’s metabolism. The several hormones I produce help transport energy to every cell in your dog’s body and they play a vital role for making your dog feel happy and healthy. Need an example? My hormones play a main role in the development of your dog’s nervous and musculoskeletal system and it’s thank to the hormones I produce that your dog gets to enjoy a normal cardio-respiratory function.
I also help regulate your dog’s temperature and work like a thermostat. You see, the hormones I produce allow your dog to generate heat and maintain an ideal temperature. If your dog is mostly kept outdoors, that means extra work for me, as I will have to increase your dog’s metabolic rate to keep him warm. Hopefully, owners of outdoor dogs will keep this in mind and feed their dogs more food to compensate for all the burned nutrients used to accomplish all this!
Oh, and if your dog has a nice coat, you must thank me as my hormones help with the anagen growth phase of your dog’s hair cycle.
When Things Go Wrong
When I produce just the right amount of hormones, everything is fine, but sometimes I may produce too many or too little hormones. Cats are notorious for having an over reactive thyroid gland (hyperthyroidism), while in dogs, the opposite is true,as they are mostly affected by an under active thyroid gland (hypothyroidism).
What happens in this case? Most often, this condition arises when the dog’s immune system attacks me, and ends up killing my cells, leading to a condition known as autoimmune lymphocytic thyroiditis. However in some cases, I may atrophy for unclear reasons or cancer may be the culprit to my destruction.
Sometimes, certain medications are known to lower my production in thyroid hormones. For instance, moderate and high doses of glucocorticoids and sulfa antibiotics are known to lower T4 concentrations while phenobarbital has shown to lower T4 levels in 40 percent of dogs taking this drug.
Regardless of what slows me down, the effects on the dog’s body remain almost the same. Since I reach all tissues of your dog’s body, when I get sluggish and stop working as I should, I cause a vast array of symptoms such as hair loss, lethargy, weight gain, recurrent skin infections, intolerance to cold, slow heart rate, dry coat and behavior changes. In some cases, I may cause drooping skin of the dog’s chin, neck and face, which is known as “tragic face” as it gives affected dogs a sad look on their faces, explains Dr. Ralston. You can see an example of this in the picture on the left.
Diagnosing dogs with hypothyroidism requires a blood test to check for signs of me not working as I should. Your vet may offer several tests, but if you are looking for the most comprehensive test in the market, you can’t go wrong with the Thyroid Profile 5™ produced by Hemopet. What the treatment for hypothyroidism in dogs? Since I am not producing hormones as I should, dogs are often placed on a daily dose of a synthetic thyroid hormone such as levothyroxine that will need to be taken for the rest of the dog’s life.
Did you know? Hypothyroidism is the most common endocrine disorder affecting dogs, and up to 80 percent of cases are caused by autoimmune (lymphocytic) thyroiditis, explains Dr. Jean Dodds.
- DVM360, Progress in the diagnosis and management of canine hypothyroidism (Proceedings), by Peter Kintze, DVM, DACVIM retrieved from the web on October 31st, 2016
- Clinical Veterinary Advisor: Dogs and Cats, By Etienne Cote, Mosby; 3 edition (December 23, 2014)
Wikipedia, Thyroid and parathyroid. Public Domain