Could your dog be hypothyroid ?
Hypothyroidism is a condition which typically affects middle-aged, medium-large breed dogs although smaller breeds can also be affected. It is caused by a decreased production of thyroid hormone (thyroxine) from the thyroid gland located in the neck, Thyroid hormone plays an important role in the body - it regulates your dog’s metabolism. Metabolism can be thought of as the car engine of the body. The thyroid gland acts as a regulator of the speed of the thyroid gland similar to the accelerator pedal altering the speed of the engine. In hypothyroidism there is too little thyroid hormone which causes changes in metabolism (it slows down) and a wide range of signs. These develop gradually, often over many months or years, and may sometimes be missed or attributed to old age. Part of the routine checks undertaken at annual health examinations involve the regular weighing of a dog. Slow and insidious weight gain is often missed without this essential (and very simple) check. If an upward trend in weight gain is starting to be noticed despite an attention to diet then alarm bells should ring.
What are the signs of hypothyroidism ?
Dogs with hypothyroidism tend to be lethargic or sluggish and reluctant to go out for walks. Often an owner will report that they seem to ‘run out of puff’ very quickly on walks, which is why it is often mistaken for a sign of growing old. Often, as a result of this apparent lethargy, it can also be mistaken for heart problems. In some instances this may make owners reluctant to seek advice, fearing the worst. Hypothyroid dogs usually gain weight even though their diet has remained the same and some dogs will fail to lose weight despite having their food intake reduced. Dogs with hypothyroidism may become more sensitive to the cold e.g. lie close to the central heating to stay warm.
Changes in the skin and hair coat are very common signs of hypothyroidism. Affected dogs can have dry, dull coats and patchy areas of hair loss. The hair loss is often first noticed in places undergoing friction, such as the neck in dogs wearing collars. In others hair loss may be evident over the elbows. Sometimes the skin can even appear thicker than normal, giving dogs a heavy-faced appearance. It is described in some cases as a dog having a “tragic face” appearance.
How is hypothyroidism diagnosed ?
The clinical signs described above give us Vets a hint that a problem may be present. A simple blood test in the first instance will then help to further confirm the diagnosis. Because there is a natural daily fluctuation in the amount of thyroxine a dog produces the full diagnosis requires what is called a ‘thyroid function blood test’. All that involves is two blood samples, before and after an injection to stimulate the thyroid gland in to action. If the “boost” in thyroid output doesn’t occur as expected then it is a pretty good indicator that there is something going wrong with the thyroid gland. However, the thyroid gland is very sensitive to other conditions elsewhere in the body so sometimes a range of tests need to be performed as the thyroid hormone level can be altered by these other conditions. It can be a little frustrating for an owner not to get a clear answer with just one blood test, but thyroid function can be very variable, making single blood sample diagnoses fraught with dangers.
How is hypothyroidism treated ?
Hypothyroidism can be easily managed but needs lifelong treatment and consists of hormone replacement tablets with a synthetic thyroid hormone. Initially a dog will require regular visits to the Veterinary Centre for monitoring which are vital if treatment is going to be successful. Your dog’s thyroid hormone level will need to be measured to determine if the dose of medication needs changing. Once the appropriate dose has been determined though, usually only routine visits are needed often spaced a six month intervals.
© copywrite Dai Gittins MRCVS.
