Symptoms of Hypothyroidism in Dogs

Hypothyroidism in dogs is an endocrine disorder that is easy to diagnose and responds readily to treatment. Dog thyroid problems are common, and can manifest in a variety of symptoms. Here's what you should know about hypothyroidism in dogs.

Canine Hypothyroidism Explained

Your dog's thyroid gland is located in his throat, and it produces the hormones that regulate his metabolism. Hypothyroidism occurs when you dog's thyroid gland produces too few of these hormones. Most cases of dog hypothyroidism occur when the thyroid gland suffers damage, whether by an atrophy of the tissues themselves, an autoimmune disorder, or a cancer. Vets don't really know what causes hypothryoidism, but they suspect that most cases of this dog disease are the result of an autoimmune disorder in which the dog's own cells attack his thyroid gland.

Hypothyroidism can occur as a side effect of certain medications, or in conjunction with another disease.

Hypothyroidism is most common in dogs four to ten years of age. Large and mid-sized breeds are more prone to the disease than toy and miniature breeds. Breeds that seem genetically predisposed to develop dog thyroid problems include:

  • Golden Retriever
  • Airedale Terrier
  • Cocker Spaniel
  • Miniature Schnauzer
  • Dachshund

Mixed breeds develop hypothryoidism less frequently than do pure breeds. Spayed females also seem at higher risk for the disease than intact females.

Symptoms and Diagnosis of Canine Hypothyroidism

Thyroid hormones are essential for regulating your dog's metabolism. Hypothyroidism affects all of your dog's body systems and organs, resulting in wide variety of non-specific symptoms. Some of these symptoms are more common than others, but when several of them occur at once, veterinarians suspect hypothyroidism. The symptoms are:

  • Lethargy and mental dullness
  • Hair loss
  • Weight gain
  • Dryness of coat and excessive shedding
  • Changes in pigmentation of the skin
  • Intolerance to cold
  • Reduced heart rate
  • High levels of blood cholesterol
  • Anemia

Diagnosis of hypothyroidism in dogs is made through blood tests. Vets use several different tests when checking for hypothyroidism. The most common are the baseline T4 test and the baseline T3 test, which test the levels of T4 and T3 thyroid hormone in your dog's blood. If either of these tests comes back positive, your vet might use another, more specific test, to confirm the diagnosis.

The TSH test measures the level of TSH, a hormone that stimulates the thyroid gland, in your dog's bloodstream. If your dog has high levels of TSH in his blood, along with low levels of T4 or T3, it's likely that he's suffering from hypothyroidism.

Treating Canine Hypothyroidism

Fortunately, hypothyroidism in dogs is easy to treat. Your dog will need a daily dose of the synthetic thyroid hormone thyroxine. Dogs with hypothyroidism need to receive this drug for the rest of their lives.

The dose and frequency of dosage of this drug varies from one dog to another, depending on the severity of the thyroid disease and the individual dog's response to treatment. It may take some time to get the dose just right. However, once treatment is started, symptoms will begin to resolve. Most dogs with hypothyroidism live healthy, normal lives once they begin to receive synthetic hormone therapy.