Hyperthyroidism

Hyperthyroidism (an over-active thyroid gland) is a very common disease of older cats.  It is caused by a benign tumour of the thyroid gland producing excessive amounts of thyroid hormone.  No one knows yet why these cats develop tumours of their thyroid gland.  The thyroid glands sit under your cat's neck on either side of the trachea (wind-pipe).  Sometimes you can feel an enlarged thyroid gland by running your hand down your cat's neck.

The thyroid hormone regulates your body's basic rate, or metabolism.  Some people get an under-active thyroid gland - Hypothyroidism - they feel sluggish and put on weight easily and need to take supplemental thyroid hormone.

Cats have the opposite problem - with Hyperthyroidism their bodies are racing on fast-forward!  They lose weight despite eating loads, their digestive system runs too fast and they get diarrhoea, and sometimes even vomiting.  They are very bright and active, and sometimes very vocal - meowing loudly!  The danger is that their hearts are also running on fast-forward.  Their heart rate increases - sometimes above 240 beats per minute, their heart enlarges, and their blood pressure reaches dangerously high levels.  They can go into sudden heart failure, or suddenly become blind if the high blood pressure in the eyes 'blows' the blood vessels in the back of the eye.  The high blood pressure also damages kidneys.

A vet will be able to do a blood test for hyperthyroidism and usually a routine blood screen will be done to make sure there are no other diseases as well. 

Fortunately once diagnosed management is very successful.  There are tablets available which stop the thyroid producing so much thyroid hormone.  Your cat needs to stay on these for life, as they will only manage the condition, not cure it.  If your cat is not great with tablets then surgery can be performed to remove the affected thyroid gland.  Radioactive iodine treatment to destroy the thyroid gland can also be carried out.  This option is only available through certain Specialist centres.

For more information about living with a hyperthyroid cat, visit www.hyperthyroidcat.co.uk