By Audrey Frederick
It is a disease named after a neurosurgeon who first described this disease in humans about 100 years ago. Cushing's disease is a disorder of the adrenal glands, a pair of bean shaped structures sitting just above the kidneys.
These glands like other glands in the feline endocrine system manufacture and secrete hormones directly into the bloodstream that facilitate and regulate a bunch of bodily processes.
Of the many hormones that are secreted, one of the most important ones is a hormone called "cortisol" - a hormone that is involved with the metabolism of carbohydrates, fats and proteins. It also helps maintain normal blood sugar levels, muscle development and many of the other things related to tissue growth and repair.
And if that is not enough cortisol also is essential in an animal's "fight-or-flight" response. In stressful situations, the adrenal glands bring additional cortisol into the bloodstream, which in turn releases stored energy, that is in the body to help a cat cope with the situation it is in. It can also help fight infection in the case of sickness or surgery.
Since this hormone is of such importance to a cat's system, it needs to be controlled in a proper manner as is flows through the cat's system. An excess of this hormone can be very dangerous for a cat. An excess can cause the cat's body not to metabolize nutrients properly, diminish cardiovascular efficiency, reduces muscle strength, interferes with normal blood-clotting functions and hurts the body's ability to ward off infection.
What are the symptoms of Cushing's disease? A cat with Cushing's disease may show an increase in thirst, increased appetite, excessive urination, a potbelly and its skin may bruise or rupture during routine handling.
You may realize from reading the above that some of the symptoms sound like diabetes and that is true, due to the excess cortisol on the blood-sugar metabolism, up to 90 percent of cats with this disease become diabetic.
Cat's with advanced cases of Cushing's disease may also develop hair loss that tends to show up on both sides of the body or on the inside of the thighs. The areas will not itch (unless there is a skin infection, too) it is just a response to too much cortisol in the body.
This disease usually occurs when cats are middle-aged or older and is usually found more in females than males.
According to the reports that I have read, there are two types of cancers that can cause this disease, one is a small, benign, slow growing tumor in the pituitary gland. It is very small and does not cause any type of neurologic problems for the cat, the only thing it does is create an over abundance of adrenocorticotropic hormone, (ACHT) which in turn tells the adrenal glands to produce more cortisol. As a result the adrenal gland will get bigger because of all the exercise (just like a muscle will.)
This condition is called pituitary-Cushing's disease and is believed to be the cause of 80 percent of the cases of this disease.
The other 20 percent of cases are caused by cancerous growths on one or both of the adrenal glands, which causes the gland to become enlarged and thus produces excess cortisol. This type of cancer has a 50-50 chance of being benign or malignant. If it is malignant chances, are it will spread to the lymph nodes or the liver and other vital organs.
What are the treatment options? First of all the disease has to be diagnosed. This is done by having a complete blood count, a blood chemistry panel, urinalysis and a few other tests done.
If Cushing's disease is diagnosed, treatment may involve drugs that will selectively destroy part of the adrenal gland that is producing too much cortisol. Drugs seem to work much better on dogs with this condition than on cats. Unfortunately surgery is usually the answer for cats.
Since the pituitary tumors are too difficult to remove, the alternative is to remove one or both of the adrenal glands. This surgery requires extensive postoperative care. The surgery will only work if the cancer has not spread to any other parts of the body.
The prognosis for survival is quite good, although cats having this surgery will have to be on medication for the rest of their lives and must have tests several times a year to evaluate their condition. Diabetic cats must have their blood chemistry, water consumption and urine output monitored frequently.