For all the owners of chronically itchy dogs and other weird issues, you may want to have a read. I don't pretend to know the endocrine system, but trying to get this pup diagnosed over the course of the last 3 years forced me into alot of research.
Thyroid conditions seem to be on the rise - and not always easy to diagnose. We should all know by now that every dog has a thyroid, but do we understand the function of this little organ and what failure of said organ (or organs that affect the thyroid) can do to your dog. The more I read these forums, the more I scratch my head and wonder if some of these dog have issue with the thyroid gland.
Typically, a vet will run what is called a T4 in order to test levels of thyroid hormone in the body. This comes back "normal", vet declares the dog fine and here's some meds for the itching and chewing. The T4 is only a small part of the story - and is only good to check for "Primary Hypothyroidism"
- failure of the thyroid to produce the necessary hormones.
There is "Secondary hypothyroidism"
- which is what we are dealing with - and is much harder to pin down but many of the symptoms are the same. T4 is pretty much in the normal range - but T3 and TSH (thyroid stimulating hormone) levels require testing as well. This is typically due to a pituitary issue in that it can't release the necessary TSH and the dog can't effectively use the thyroid hormones. Even then a leap of faith is generally necessary to get a positive diagnosis in the dog - a trial of synthroid.
There are also tertiary and congenital forms of hypothyroidism as well, you can research those on your own.
I've often wondered about physical damage to the dogs thyroid caused by collars - or dogs pulling on said collar. It makes me cringe when I see the large breeds pulling on their collar - and knowing that a damaged thyroid can cause behavioral issues. That's one of the reasons I personally don't subscribe to the use of shock collars, choke chains or prong collars etc.
You could well have a dog in a hypo condition and not know it.