HYPERADRONACORTICISM

Agility Australia (Yahoo dicussion forum) 2000

Hi all,

A couple of people have asked me a little bit about hyperA (Cushing's disease or hyperadrenocorticism.)

This is a disease due to excessive activity of the adrenal gland causing the production of too much of a group of hormones produced there - mainly cortisol. (You can get similar problems if you use too much cortisone to
treat a dog with allergies). Everyone has two adrenal glands - one sitting on top of each of our kidneys.

These hormones are involved with a wide variety of functions but can be broadly described as dealing with stress and to make sure enough energy is available.

There is a very wide variety of symptoms that may be seen, or not seen with HyperA. The most common are:

+Increased urination (for unexplained reasons) which in turn, causes    increased drinking. Increased drinking can be a sign of   MANY diseases and any dog thought to be drinking excessively should be checked by a vet even though the dog may seem otherwise well.

+Increased appetite, to the point that the dog may start to steal food.

+A big pot belly - this is associated with weaker abdominal muscles, increased fat in the abdomen and an enlarged liver. These occur because the body is breaking down too much protein to create glucose. The dog appears fat, although you will notice that the back bone is often prominent.

+There is distinct muscle weakness - the muscles are wasting away, even though the dog has a lovely fat tummy. The muscle weakness is probably not obvious to the pet owner because the dog can still get up and walk around. This muscle weakness is associated with the breakdown of protein, but also may be due to the loss of potassium from the body.

+There is often hair loss, especially from around the flanks. The skin is very thin and sometimes even see-through. There is not enough protein production to produce healthy hair and skin.

+There are a whole lot of other signs - bruising, gritty calcified sores, black heads, breathlessness, changes in blood cells, blood electrolytes and blood metabolites.

There are several long term problems that occur with hyperA - kidney infections, heart failure, calcification of soft tissue (liver etc),
neurological signs and liver failure.

There are two mechanisms by which hyperA can occur.
1. One of the adrenal glands may be overactive - usually due to a tumour. This gland produces too much cortisol so we see symptoms. If this is the case, the gland can be removed and the other one can usually function well enough to make up for the other one.

2. - The adrenal gland is controlled by the pituitary gland, in the base of the brain. If there is a tumour in the pituitary gland, it tells the adrenals to keeping on producing cortisol, even though there is more than enough. This type of hyperA is more difficult to treat (and a lot more common).

The two types of hyperA can be differentiated by a series of tests. It is very important to find out which type you are treating. Both types of hyperA can be treated although life expectancy is not necessarily great. Quality of life must also be considered.

HyperA is a fairly common problem in older (6 years+) dogs. Most practices have one or two patients that are diagnosed or suspected cases. It is not so common that you should think your dog has got it every time you see your dog take a drink of water!

BUT - in general terms, increased drinking can be indicative of a lot of problems - diabetes mellitus, diabetes insipidus, renal failure and hyperA. Quite often, dogs with these problems are still eating well (and sometimes, excessively). The owner thinks that, because the dog is eating well, there cannot be too much wrong. Increased drinking (other than on hot days!) should always be checked out by your vet.

Hope this helps

Le Hammer BVSc