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Acromegaly in cats

Acro what? What is that?
It’s an over-production of growth hormone caused by a tumour of the pituitary gland.

That sounds serious. What problems does it cause?
Lots of problems. It causes the bones and organs of adult cats to start growing again and also causes metabolic problems like diabetes.

So do you end up with a giant cat?
They do tend to be big cats  but the most obvious changes are in the head. Cats with acromegaly tend to have a long, protruding lower jaw and a very wide head. They also have large club like paws.

You mentioned  diabetes. What is the link there?
Growth hormone has an anti-insulin effect so that the insulin that the cat produces is unable to work. This causes blood glucose to rise just like in diabetes.

Diabetes in cats is treatable isn’t it?
Usually we treat diabetic cats with injections of insulin but in acromegaly insulin doesn’t work. These cats have insulin resistance due to excess growth hormone.

So is acromegaly treatable?
It’s not cureable and all we can do is to try and treat the symptoms. We use a special diet and tablets to try and lower the blood glucose. Cats with acromegaly also tend to have heart problems so we need to treat them for that too.

Why do they get heart problems?
The growth hormone causes the muscle of the heart to grow so they end up with an enlarged heart that doesn’t function properly. For the same reason they can have kidney problems too.

Is acromegaly common?
Veterinary text books tell us that it is rare but with modern diagnostic tests it has become apparent that it is a lot common than we thought. Studies have suggested that as many as 1 in 3 diabetic cats may have acromegaly.

So how is it diagnosed?
Partly on clinical signs. We become suspicious if we have a diabetic cat that doesn’t respond to insulin. We become more suspicious if the cat is gaining weight as most normal untreated diabetic cats tend to lose weight. The change in shape  of the head and jaw is a dead giveaway but this doesn’t always happen.

Are there any lab tests like testing  the level of growth hormone?
Testing growth hormone levels is not available in New Zealand but we can test for something called insulin like growth factor. It is not a specific test for acromegaly but does give us more of a clue. It is also possible to perform an MRI scan of the pituitary gland in the brain to show that it has a tumour though this is expensive and needs to be done down in Christchurch.

So to sum things up acromegaly is quite common in diabetic cats and is generally untreatable as it doesn’t respond to insulin.
Yep thats about right

And todays question?
Acromegaly is due to the over-production of a hormone. What is the name of that hormone?
 (growth hormone)
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