Diagnosing Congenital Hypothyroidism in Dogs

Hypothyroidism in dogs usually occurs in middle-aged or geriatric animals, due to reduced thyroid function. Congenital hypothyroidism is present in puppies when they are born. It is a serious condition that drastically stunts a puppy's development. Here's what you should know about diagnosing and treating congenital hypothyroidism in dogs.

Your Puppy's Thyroid Gland and Its Purpose

Your dog's thyroid gland is located in his throat, near his larynx. It is shaped like a butterfly, and wraps around the windpipe. The thyroid gland produces thyroid hormone, or TH. It's this hormone that regulates your dog's metabolic processes.

The thyroid also produces the hormone calcitonin. This hormone is responsible for regulating your dog's calcium metabolism. It's necessary for the growth, development and maintenance of bones and teeth.

How Adult-Onset Hypothyroidism Is Different from Congenital Hypothyroidism

Hypothyroidism is common is dogs. However, it most often develops in adult animals. Congenital hypothyroidism becomes evident during the first year of life and is rare.

When adult animals develop hypothyroidism, they can become very ill, due to the way the disease interrupts their normal metabolic processes. However, treatment is straightforward and usually involves administering synthetic hormone replacement drugs. Adult-onset hypothyroidism occurs because of damage to or failure of the hypothyroid gland. Adult dogs, however, have already completed their growth and development, and, with treatment, they can live with the condition happily for many years.

Puppies, on the other hand, have not yet completed their growth and development. Puppies need thyroid hormones like TH and calcitonin to regulate the metabolic processes that must occur for their development. If a puppy's thyroid gland doesn't develop and function as it should, it cannot thrive and grow at a normal rate, nor will its bones develop normally. That's why congenital hypothyroidism is a much more serious condition than adult-onset hypothyroidism.

Symptoms of Congenital Hypothyroidism in Dogs

Congenital hypothyroidism occurs within the first year of a dog's life. Puppies are born with this condition.

Puppies with hypothyroidism do not grow as quickly as they should. Their legs are often shorter than they should be. The bones of the skull may be deformed and the puppy may appear bug-eyed as the eyeballs and tongue stick out. Puppies with congenital hypothyroidism may also be mentally challenged.

Diagnosing Congenital Hypothyroidism in Dogs

A diagnosis of congenital hypothyroidism can usually be made when symptoms appear as the puppy grows older. It can be hard to diagnose this condition in newborn puppies, since is primary symptom is abnormally slow growth rate. Blood tests can confirm the absence of adequate amounts of thyroid hormone and calcitonin in your puppy's blood. 

Treating for congenital hypothyroidism is the same as treatment for adult-onset hypothyroidism. Synthetic thyroid hormone, thyroxine, is administered. For treatment to be a success, it must begin as soon as possible, preferably before three weeks of age. This can be difficult, since congenital hypothyroidism is hard to spot in puppies so young. 

Sadly, treatment for congenital hypothyroidism often fails. Puppies with this condition usually don't live to adulthood.