Symptoms of Underactive Thyroid in Dogs

The symptoms of underactive thyroid in dogs should be identified early as this disorder can affect the entire body and result in further health complications. An underactive thyroid gland results in lowered production of hormones by the gland, thus resulting in a condition known as hypothyroidism. Hypothyroidism is very common in dogs and leads to a lowered metabolic rate.


Hypothyroidism is an endocrinal disorder that affects the thyroid gland. This in turn leads to the production of insufficient amounts of the thyroid hormone, thyroxin. Hypothyroidism can adversely affect many organs of the body and can cause diverse problems.

The Thyroid Gland

The thyroid gland is situated in your pet’s neck and is butterfly-shaped with 2 lobes. An autoimmune disorder results in degeneration of healthy thyroid gland tissue. This makes the gland produce inadequate amounts of thyroid hormones.

Causes of Canine Hypothyroidism:

  • Autoimmune thyroiditis
  • Genetics
  • Pollution
  • Environmental factors
  • Idiopathic causes
  • Atrophy of the thyroid gland 
  • Chemicals

Prevalence of Canine Hypothyroidism

Certain breeds of dogs are prone to hypothyroidism. These include:
Golden Retrievers

  • boxers
  • German shepherds
  • greyhounds
  • Great Danes
  • beagles
  • cocker spaniels
  • Doberman pinschers

Miniature and toy breeds are least affected by this disorder.

Males and females are both equally affected by this disorder although spayed females are more prone to hypothyroidism than unspayed female dogs. Hybrid dogs are also less prone to this disorder than purebred dogs.

Symptoms of Canine Hypothyroidism

Symptoms of hypothyroidism are similar to those of several other diseases. Hence, it’s difficult to diagnose canine hypothyroidism. The onset of this disorder is generally at puberty and as the pet ages, his chances of being affected increase. Common symptoms include changes in the condition of the coat, weight gain, dryness of the skin and thickening of the skin.

Other symptoms include:

  • Itchiness
  • Toenails that tend to chip or get infected
  • Skin conditions such as lesions
  • Loss of hair resulting in bald spots on the trunk and hind legs
  • Loss of hair on the tail
  • Drooping of the eyelids
  • Tilting of the head
  • Facial paralysis
  • Tragic facial expression
  • Pain in the joints
  • Ear infections resulting in loss of hearing
  • Incontinence
  • Constipation
  • Nausea
  • Diarrhea 
  • Unpleasant skin odor

Changes in Behavior

Dogs with hypothyroidism are generally listless and lethargic. They also exhibit symptoms of fatigue, weakness and depression and tend to spend most of their time lying down or sleeping. They are prone to mood swings and can be aggressive towards people and other animals. Some dogs also exhibit signs of anxiety and nervousness.

They show low tolerance for exercise and cold weather. They may have low energy levels and a slow heart rate. Neurological changes such as disorientation, loss of focus, epilepsy and seizures are also exhibited by affected animals.

Dogs with hypothyroidism are often infertile. Males with hypothyroidism exhibit lower libido. As a result of atrophy of the testicles, they have lowered sperm level counts. Affected females have longer gaps between menstrual cycles and give birth to weak or stillborn pups.

Hypothyroid canines are generally anemic and prone to infections of the eyelid glands. They also lose their sense of smell and taste and have weak eyesight.

Hypothyroidism is easy to treat. Hence prompt diagnosis is essential. You should have your pet checked by the vet if you observe any of the symptoms mentioned above, in order to prevent unnecessary complications.