A relatively common hormonal imbalance in dogs (and to some extent in cats) is low thyroid levels, or hypothyroidism. Canine hypothyroidism usually shows up in middle-aged, larger breed dogs or in genetically susceptible dogs. The thyroid gland is located in the neck near the throat and is bilobed, almost ‘butterfly shaped.’
Essentially, its job is to control the idling speed for your pet’s engine. The thyroid helps regulate metabolism and metabolic rate. Almost all cases of hypothyroidism result from a condition called immune mediated thyroiditis. This occurs when the immune system starts to destroy the thyroid gland, resulting in low hormone output and subsequent loss of control of the metabolic rate. Many dogs with thyroiditis will not show symptoms until they are truly hypothyroid.
With a lowering of the idle speed of Muffy’s metabolism comes a slowing of various bodily functions. A humorous symptom listed in the literature for hypothyroidism is ‘mental dullness,’ but weight gain and/or the inability to shed weight seems to be the No. 1 symptom.
A lower metabolic rate means fewer calories are burned, period. Even when outside factors like diet and exercise remain the same, fewer calories burned means weight gain. Lethargy is also a common symptom and it can result from both the lowered metabolism of low thyroid hormone and the weight gain. A snowball effect results, with a number of dangerous side effects: orthopedic, cardiac, neurologic and others.
Dogs that are hypothyroid usually present to the veterinarian in the following way: 5 to 8 years old, surgically altered, overweight and ‘lazy,’ having a dull coat, bilateral hair loss on the flanks, and flaky skin. Skin and coat problems are prevalent in hypothyroid dogs. Hair loss and patchy bald spots appear, and sometimes the tail resembles that of an opossum or rat. Where hair is lost, it doesn’t readily grow back. Your dog may appear fluffier than normal, as if they have puppy hair. This is due to the loss of the ‘guard’ hairs, leaving the softer undercoat behind. Without the normal, protective coat—and with a challenged immune system—the skin is more susceptible to infection, causing further hair loss and flaky, scaly skin.
Thyroid hormones maintain rates and regulations of many bodily functions, not just skin and hair coat. There is even a correlation to seizure activity. All dogs experiencing seizures should be checked for thyroid function on top of the normal blood tests run when checking out the causes of seizures. Sometimes when you fix the thyroid problem you resolve the seizures as well. I love it when that happens.
Some breeds—like golden retrievers, boxers, Great Danes and Doberman pinschers—are predisposed to hypothyroidism. Smaller breeds aren’t excluded, as dachshunds, miniature schnauzers and poodles have a predilection for the disease as well.
Discovering hypothyroidism is noninvasive and easy. A simple blood sample is collected and sent to the lab for analysis. But don’t rely on just one or two thyroid values; a comprehensive report of several different thyroid hormones is more accurate. You’ll get the real answer faster, which is what is best for your sick pup.
Treatment is usually simple and effective. Supplement your dog’s failing thyroid with a synthetic thyroid hormone pill and you’ll get your glossy-coated, skinny, active little fun-lover back. I love it when that happens, too!