Hypothyroidism (Thyroid hormone deficiency)

Thyroid hormone is produced by a small organ in the neck. A lack of this hormone (hypothyroidism) may cause a whole range of problems. Dogs with this disease are often mistakenly thought to be just getting old. It is worth looking out for this disease because treatment is simple – with daily tablets to replace the missing hormone your dog could be given a new lease of life.

The thyroid gland is a small organ in the front of the neck just around the voice box. This gland makes thyroid hormone and releases it into the blood in a carefully controlled way. Just the right amount of hormone is released in order to keep your dogs body working at the right rate.

Thyroid hormone is essential for the normal functioning of the body, affecting almost all cells and organs. It is particularly important for controlling the heart rate and the activity of cells. When there is more thyroid hormone the cells work harder and burn more energy, when there is less the whole body slows down.

There are a number of reasons why a dog might not produce enough thyroid hormone. In most dogs, it is just because the thyroid gland has been damaged and does not work as well as it should. Very rarely the problem can be due to a cancer of the gland or abnormal development of the hormone system in a puppy.

A lack of thyroid hormone in the body is called hypothyroidism. Often the symptoms of a lack of thyroid hormone are not very obvious. The problem is usually seen in middle-aged or older dogs and quite often the symptoms come on so slowly that owners simply think their dog is just getting a bit old. Dogs tend to slow down a bit and be less keen to run around. Additionally, their appetite is usually normal but they may put on weight because they are not exercising normally.

Other common changes associated with the disease are bald patches on the body, other skin problems, or feeling the cold more than normal. Sometimes dogs with long coats (like Retrievers) don’t moult properly and get shaggy, matted coats.

This disease can be a bit tricky to diagnose. Blood tests and skin biopsies can help your vet, but most often the final proof is found by measuring the level of thyroid hormone in the blood.

There is no treatment which will make your dog’s thyroid gland start to work normally again. However, it is very simple to replace the missing hormone by giving hormone replacement tablets. These tablets will need to be given at least once (and often several times) every day for the rest of your dog’s life. However, once your dog is receiving these tablets they should get back to their normal self very quickly.

Your dog should be happier and more active within a few weeks and if they had other symptoms (like skin disease) this should get better within a few months. Your vet will probably want to keep a check on your pet and may need to take several blood samples to ensure that the tablets are working properly but, after this, the long term outlook for your dog is very good.