Hypothyroidism in Dogs
Hypothyroidism in dogs is rather common, especially among older dogs. It is a disease of the thyroid gland. Hypothyroid dogs suffer from a deficiency of the hormone thyroxine (T4). This page looks at the symptoms, causes, and treatment of canine hypothyroidism.

The thyroid gland is responsible for the production of the hormones thyroxine (T4) and triiodothyronine (T3). These hormones have very important functions – they control the body’s metabolic rate.

Hypothyroidism is a disease of the thyroid gland. Hypothyroid dogs suffer from a deficiency of the hormone thyroxine. As a result, these dogs have lower than normal metabolic rates.

Canine hypothyroidism usually occurs in middle-aged dogs. Although all breeds can develop hypothyroidism, there are certain breeds of dogs that seem to be more prone to the disease.

The breeds most commonly affected are:

  • Golden Retriever
  • Labrador Retriever
  • Dachshund
  • Miniature Schnauzer
  • Shetland Sheepdog
  • Irish Setter
  • Cocker Spaniel
  • Greyhound
  • Doberman Pinscher

Possible Causes of Hypothyroidism in Dogs

The most common cause of canine hypothyroidism is autoimmune thyroiditis (aka lymphocytic thyroiditis), which is an autoimmune disease in which the body attacks its own thyroid gland, causing the destruction of the gland tissue.

A small number of cases of canine hypothyroidism is caused by the atrophy of the thyroid gland due to unknown reasons.

It is not clear as to the underlying causes of these two types of thyroid gland atropy, but many veterinarians believe that factors such as toxins in the environment (e.g. pesticides, food preservatives, household cleaning chemicals), medications, and poor diet are all possible triggers.

Symptoms of Hypothyroidism in Dogs

A classic symptom of dog hypothyroidism is hair loss which is bilateral and symmetrical. The hair loss occurs primarily over the body, sparing the head and legs. So it may involve the two sides of the dog’s body, the front of the neck down to the chest, or the top of the tail. The remaining hair is dry and sheds easily.

Some dogs will have thickening and drying of the skin and increased skin pigment, and may develop secondary skin infections.

Besides hair loss and skin problems, hypothyroid dogs may also show the following signs and symptoms:

  • Weight gain (without appetite increase)
  • High cholesterol levels
  • Intolerance of cold temperatures
  • Lethargy and mental dullness
  • Intolerance of exercise
  • Infections (such as ear infections and skin infections which may cause itchiness)
  • Behavior changes (e.g. aggression)

Treatment of Hypothyroidism in Dogs

Conventional treatment of canine hypothyroidism is thyroid hormone replacement by orally administering synthetic L-thyroxine (L-T4) once or twice a day, for the rest of the dog’s life.

The dog’s condition will be monitored carefully and frequently, especially during the early course of treatment. It takes about 4 to 6 weeks for hair loss and other symptoms to improve.

A Natural Product for Hypothyroidism in Dogs

If your dog’s thyroid hormone level is a bit on the low side but not low enough for hormone therapy treatment, you may want to look at this natural product that can help your dog – be sure to discuss the pros and cons of using the product with your vet:

Thyroid Support Silver for Dog Hypothyroidism

This is a natural herbal formula that helps to maintain and support a healthy thyroid gland and helps the body to produce thyroid hormones on its own.