Congenital Hypothyroidism in Dogs

Hypothyroidism in dogs usually occurs in adult dogs, mostly dogs middle aged or older. Congenital hypothyroidism is more rare and occurs in puppies. Usually congenital hypothyroidism occurs because a puppy's thyroid gland has failed to develop properly.

Understanding the Canine Thyroid Gland and Its Diseases

Your dog's thyroid gland is a small gland located in the throat, and its function is the production of the thyroid hormone thyroxine. Your dog's thyroid gland also produces a hormone called calcitonin, which helps your dog's body metabolize calcium.

Thyroid hormones help to regulate your dog's metabolism. Too much thyroid hormone causes canine hyperthyroidism, a condition that makes your dog lose weight despite a significant increase in appetite. It causes hyperactivity in dogs. Too little thyroid hormone causes canine hypothyroidism, as condition that makes your dog gain weight despite no obvious increase in food consumption. Dogs with too little thyroid hormone become lethargic and may seem depressed.

In adult dogs, thyroid dysfunction occurs as a result of damage to the thyroid gland, whether by cancer or by autoimmune disease. Since your dog's thyroid function is linked to the adrenal and pituary glands, damage to these glands may also result in thyroid dysfunction.

Adult canine thyroid dysfunction can be easily treated with medication. Congenital hypothyroidism in puppies, however, is the result of improper development of the thyroid gland, and most puppies afflicted with congenital hypthyroidism don't live to adulthood. The disease must be diagnosed within the first three weeks of life for treatment to be successful, and the symptoms are difficult to distinguish in puppies so young.

Symptoms of Congenital Hypothyroidism

Puppies suffering from congenital hypothyroidism won't grow as fast as they should. They may have unusually short legs and the bones of their skulls may grow abnormally and become deformed. Abnormalities in the bones of the skull can cause puppies suffering from congenital hypothyroidism to have bulging eyes and a protruding tongue. Puppies with congenital hypothyroidism may also suffer from cognitive impairment, because their brains won't develop at the appropriate rate.

Risk Factors for Congenital Hypothyroidism

Some breeds are more prone to congenital hypothyroidism than others. These breeds include the German Shepherd, Giant Schnauzers and Toy Fox Terriers. Dogs who produce puppies with congenital hypothyroidism should not be bred, and neither should their parents or siblings, because the disease is hereditary.

Diagnosing and Treating Congenital Hypothyroidism in Dogs

Diagnosing this disorder is difficult, as symptoms are usually not obvious in newborn puppies. Unlike treatment for adult forms of thyroid dysfunction, treatment for congenital hypothyroidism is difficult and almost always unsuccessful. Most puppies with congenital hypothyroidism do not live to adulthood. Treatment must begin very early in life in order to be successful. Puppies must begin treatment for congenital hypothyroidism at no later than three weeks of age if they are to survive to adulthood.

If a puppy is diagnosed with congenital hypthyroidism before three weeks of age, the medical treatment calls for thyroxine supplements.