What is Hypothyroidism?
The thyroid gland is a gland located in a dog’s neck below the “Adam's Apple” on either side of the windpipe (trachea) that is responsible for producing thyroid hormone, which regulates metabolism (and other functions, too). The thyroid gland therefore plays an important role in every cell in the body.
When the gland is under-producing thyroid hormone, the condition is called Hypothyroidism, which is one of the most common hormonal problems in dogs.
Most often, the cause of the low levels of thyroid hormone production are from destruction of the thyroid gland by a dysfunctional immune system or a dietary iodine deficiency. A congenital condition would be a less common cause.
Hypothyroidism generally develops in middle-aged or older dogs; these breeds are predisposed to the condition:
What Are The Signs / Symptoms Of Hypothyroidism?
The most common findings for dogs with Hypothyroidism are:
- Skin abnormalities such as oily skin, scaly skin or dry skin
- Recurring skin infections
- “Rat Tail” Hair loss (most commonly, the tail loses hair first)
- Unexplained weight gain
- Lethargy / Tiredness
- Cold avoidance (dog always seeks warmth)
As you can see, the signs can be subtle and are often confused with other conditions. The clues of hypothyroidism are often first picked up at yearly wellness checks by your veterinarian. Dogs with hypothyroidism often have very slow heart rates, for example.
How Is Hypothyroidism Diagnosed?
Where skin abnormalities are present, often the skin complaint will have been treated as the primary problem. If the skin condition doesn’t go away with treatment or continues to recur despite treatment, then it is worth testing for hypothyroidism. Middle-aged, overweight dogs (especially in the breeds above) are candidates for screening.
During basic screening, standard blood work may point to the need to run further thyroid function tests. Without going into too much detail, high blood cholesterol and mild anemia (low blood cell count) are some of the conditions that may be seen on the standard blood work.
If your veterinarian suspects hypothyroidism, most will run a thyroid function blood test via an external laboratory.
How Is Hypothyroidism Treated?
The treatment, which is much more straightforward than diagnosing the condition, is oral administration of thyroid hormone (T4). Regular monitoring is required; once the condition is under control, dosages can often be decreased.
Treatment is given for the rest of the dog’s life. Most dogs respond well to treatment; noticeable improvements in mental alertness and activity levels occur shortly after treatment has started.