Pet Vet: Scottie's changes point to Cushing's disease

November 24, 2014

Mac is a 10-year-old Scottish terrier who has lived with Joe and Paula for almost all of his life. He has always been a healthy dog. Joe and Paula give Mac a monthly tablet for prevention of heartworm disease and intestinal parasites as well as a monthly topical flea preventative. He is fed a good diet and is not allowed to eat from their table. Recently, Mac has displayed some changes in his body and his habits and Joe and Paula are concerned.

Mac has begun to lose hair mostly on his sides and he seems to be getting a bit portly. He has been stout as described by Joe and Paula, all his life but lately he looks like he’s getting fat. He has become a much more aggressive eater and his thirst has become increased as well. Through their research, Joe and Paula have concluded that Mac might have Cushing’s disease and wanted some advice on how to proceed. Their need for veterinary intervention is obvious and acknowledged by Joe and Paula, but they would like to be educated on the diagnosis of Cushing’s disease as well as its treatment. They would also like to know if there might be another possible cause for the changes in Mac’s stature and behavior.

I must commend Joe and Paula on their active role in trying to determine what might be Mac’s problem. When caretakers are familiar with their companions and the changes that are apparent, it can make our jobs as veterinarians and investigators much easier. Joe and Paula are of course correct in surmising Mac’s need to see his veterinarian, and they are also correct in their conclusion that he may have Cushing’s disease.

Cushing’s disease is something we have discussed here before but some of the information bears repeating. This disease is one of the more common in the group called endocrine disorders. These diseases involve hormone systems in the body. In the case of Cushing’s disease, the specific area of concern involves the adrenal gland or glands and sometimes the pituitary gland. The "technical" name of the disease is hyperadrenocortisism. This is because it involves increase in the size and production of the area in one or both adrenal glands responsible for producing cortisone. With this increase in produced cortisone, the symptoms of Cushing’s disease occur. These include increased appetite and thirst, increased panting, thinning and loss of hair over time, usually equally on both sides of the body, development of a pot-bellied appearance, and thinning of the skin. Any or all of these symptoms can occur with this disease. Mac’s symptoms as described by Joe and Paula certainly do fit.

There are two types of Cushing’s disease. One type involves the development of a tumor in the pituitary gland in the brain that produces an excess of a hormone called adrenocorticotropic hormone (ACTH), which stimulates part of each of the adrenal glands to produce too much cortisone. The other form of the disease involves the development of a tumor in one of the adrenal glands that directly produces excess cortisone and causes the disease. The pituitary form of the disease is far more common.

To diagnose Cushing’s disease, we use blood samples testing for the presence of cortisone in the blood before and after stimulation of the adrenal glands. If the testing is positive, treatment for the disease can be initiated and is usually effective in eliminating the symptoms. Not all dogs that are positive for Cushing’s disease need to be treated right away. It depends on the severity of the symptoms and which type is involved. Of the two forms of the disease, the pituitary form is more amenable to treatment with medication. An important point to understand about this form of the disease is that it is not considered curable. It can be effectively treated. The adrenal tumor form of the disease is curable in some cases by removal of the tumor, although some of these tumors are not amenable to surgery.

As far as the possibility of another disease causing Mac’s symptoms, diabetes and low thyroid condition are two that come to mind. I strongly suspect, as do Joe and Paula, that Mac has Cushing’s disease.

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