While some skin conditions such as a flea infestation are obvious signs of skin allergy and related secondary conditions, many ‘skin allergy’ conditions can actually be things that are more serious and more dangerous to your dog.
Sometimes skin allergies can be combined with other medical conditions.
Skin scrapings and fungal tests are typically the first two tests performed for dog skin allergies that can reveal other causes rather than actual skin allergy things – however one big one that vets are using is a thyroid test.
Why thyroid testing for dogs with skin allergies?
Hypothyroidism (An under active thyroid gland on your dog) can cause skin conditions (that look like allergies), although dogs with ONLY hypothyroidism are usually not very pruritic (skin condition most common with skin allergy).
The thyroid gland is a small gland located at the throat), – it has two lobes, and can be felt with careful palpation.
The most common hormone problem in dogs is hypothyroidism. This term is when the thyroid gland does not secrete enough of the thyroid hormone called thyroxine. When this happens many internal organs of the dog are affected. The thyroid gland takes iodine (usually collected from food intake) and converts it into the two main thyroid hormones; thyroxine (T4) and triiodothyronine (T3). T4 & T3 then course through the bloodstream and affect the metabolism of EVERY cell in the body. This is why either under or over creation of these hormones is bad.
The control the level of these hormones (T3 and T4) happens in the hypothalamus (brain part) and pituitary (another gland) that secretes chemicals called releasing factors.
While the hypothalamous and pituary control other functions in the body for the thryoid gland, they secrete a releasing factor called thyroid stimulating hormone (TSH).
It is the amount of TSH in the blood stream of your dog that that tells the properly functioning thryoid gland how much thyroxine to secrete. Thyroxine circulates throughout the bloodstream and affects almost all organs. It plays a major role in controlling metabolism, and is needed for growth of all cells.
It is a curious artefact of the symptoms of hypo-thyroidism (too little thyroxine) that the skin of the dog is altered to mimic allergy symptoms.
Thyroxine affects many internal dog organs including mental dullness, lethargy, obesity, and heat seeking behavior although not in all dogs.
One symptom shared by many dogs is skin symptoms that can include symmetrical hair loss (alopecia) along the dog trunk. You will find that a dog with hypo-thyroidism has hair that easily falls out, grows back slowly, and sheds more often.