Cushing's Disease in Dogs
First, a little lesson in basic endrocrinology (and this is really basic). The endocrine system is a group of glands; each is responsible for secreting various hormonal substances that help other systems function normally. The whole system is governed by the pituitary gland. Its location at the base of the brain highlights its importance. The pituitary gland monitors the level of different substances in the body secreted by other glands. When it detects a low level of any given substance, it secretes a stimulating hormone that causes the gland producing that substance to produce more. When the level is high enough, it tells the gland to stop producing.

Symptoms of Cushing Disease Increased thirst Increased urination Increased appetite Panting High blood pressure Thinning of coat Pendulous abdomen Thinning of skin Skin infections Muscle weakness Recurring urinary tract infections and many more

The adrenal glands (one on each side of the body just above the kidneys) produce a wide range of hormones responsible for maintaining many body functions. In Cushing's disease (also known as hyperadrenocorticism), these glands produce more of these hormones than they should. Because of the variety of systems affected by the production of adrenal hormones, symptoms of Cushing's disease can vary widely (see inset). Left untreated, Cushing's disease will progress and lead to life-threatening disorders including diabetes, nervous system diseases, congestive heart failure, and liver and kidney failure. (Cushing's disease has been seen in cats but it is uncommon.)

There are three possible causes of Cushing's disease.

• Iatrogenic Cushing's - overuse of cortisone-type hormones - This is the easiest to treat. It is caused by the over-administration (either orally or by injection) of corticosteroids such as prednisone. Very slow reduction of the corticosteroids generally allows the adrenals to return to normal hormone production. However, there are some cases in which the overuse of these cortisones has already caused other systemic problems that cannot be reversed.

• Adrenal-dependent Cushing's - This is the result of a tumor of the adrenal gland and covers 15-20% of the cases of Cushing's. The tumor is often large enough to be seen by x-ray or ultrasound and may be malignant. Surgical removal of the affected gland is a treatment option.

• Pituitary-dependent Cushing's - 80- 85% of the cases of Cushing's is caused by the presence of a tumor of the pituitary gland. This tumor is most commonly benign, but it causes the pituitary gland to over-stimulate the adrenal gland, resulting in an overproduction of the adrenal hormones. Surgical removal of the pituitary gland is not an option. There is a treatment option involving radiation therapy, but a more exact diagnosis is needed before that therapy is recommended. A CT scan would be required to make that diagnosis. The most common therapy for Pituitary-dependent Cushing's involves attempting to control the activity of the adrenal gland.

Diagnosis of Cushing's disease is made through the use of several blood and urine tests. These tests will require the patient spending the day at the hospital (not overnight). Based on the results of these tests, the veterinarian may recommend x-rays and/or ultrasonography to determine the presence of an adrenal tumor.

Treatment will depend upon the type of Cushing's. Treatment options for Iatrogenic Cushing's and Adrenal-dependent Cushing's have already been discussed. In Pituitary-dependent Cushing's, since the pituitary gland cannot be surgically removed or treated directly, the veterinarian must use medication directing the adrenal glands to reduce the production of their hormones. This is not a cure since the pituitary gland will still be signaling the adrenal glad to overproduce, but we can reduce the symptoms of Cushing's and the potential for other life-threatening disease processes. The most common medication used for treatment of Cushing's disease is mitotane, also known as Lysodren™. Careful monitoring of the patient undergoing treatment for Cushing's is extremely important. Too little medication will result in a persistence of the symptoms (and in turn, other serious conditions caused by the over-activity of the adrenal gland). Too much medication can destroy the adrenal gland itself, which can also be life-threatening. Also, there can be some serious side effects from use of Lysodren.

There are two other medications being used in the treatment of Cushing's which are showing great promise. One is Ketoconazole, originally used for treatment of systemic fungal infections. A side effect of this medication (noticed in use in humans) indicated to researchers that it might be useful in the treatment of Cushing's disease. Although there are still some side effects connected with Ketoconazole, it has a much higher safety margin than Lysodren. The drawback of this medication is its expense.

The other medication being used today is l-deprenyl, or Anipryl. This drug, through a complicated chain of actions, reduces the pituitary gland's stimulation of the adrenal glands, thus reducing the hyperactivity of the adrenal glands. The safety margin of this medication is high and the side effects are low and minor in their effect on the patient. Although this medication is more costly than Lysodren, it is much more affordable than Ketoconazole.

Prognosis for patients with Cushing's disease is guarded since treatment is not curative, and control is sometimes difficult. Early diagnosis and careful monitoring of patients during treatment greatly increase their chance of a good quality of life.

The symptoms of Cushing's can be seen in a variety of disease processes. Because Cushing's is more commonly seen in pets over ten years of age (although it can be seen as young as six years), many pet owners will assume it is just "old age". Remember, old age is not a disease. The symptoms you might consider normal in your senior pet should really be cause for concern. Early diagnosis and treatment can greatly improve your pet's quality of life. And aren't they worth it?!?

Photo taken from Current Veterinary Dermatology by Craig E. Griffin, Kenneth W. Kwochka, and John M. MacDonald.

Meet Alice Sparks
Kim Sparks speaks on her greyhound Alice (left), and answers some questions about greyhound ownership:

"Being able to bring my dog Alice to work is one of the most rewarding aspects of my job, but it has also raised questions from many of our clients. Dog racing is very controversial, and because of this, many rumors and myths have been created about the sport and the athletes, the greyhounds. I'd like to clarify some of those myths, and show how rewarding owning a greyhound can be!"

Eight Common Myths about Retired Greyhounds

1. Greyhounds need LOTS of exercise.
False! Greyhounds are the biggest couch potatoes you will ever meet. Alice's favorite pastime is snoozing on her couch. She's so lazy she even prefers to eat her meals lying down! Just like any dog, Alice does enjoy playing with her friend Tori, but she's normally the first one to quit.

2. All greyhounds are underfed on the racetrack.
False! Alice may look skinny, but that is the natural build of a greyhound. Their sleek muscular frames were designed to help them run fast and efficiently after prey. Don't let her skinny frame fool you! Alice eats up to 6 cups of food a day!

3. Greyhounds cannot live with cats or other small animals.
False! Alice lives with her two feline "sisters" Epona and Kalma; and is actually quite afraid of the cats! She knows who the boss is, and will make every effort to stay out of their way. Some greyhounds, however, do have such a strong chase instinct they cannot be trusted to live with cats and other small animals.

4. Greyhounds cannot live in an apartment.
False! Alice enjoys apartment living. Since most of her day is spent sleeping on the couch, she doesn't mind the smaller quarters. However, Alice, or any greyhound, cannot be allowed outside without a leash or fenced yard, which means she must be walked three to four times daily to relieve herself.

5. All greyhounds are put to sleep when retired from racing.
False! While this used to be the case several years ago, many organizations are working with the track owners to have the dogs adopted into loving homes. Alice was raced in Minnesota and was flown to a kennel in Ohio to be adopted. While waiting for adoption, she was cared for by a woman in the Mansfield Correction Center so she could be introduced into a home environment and taught basic commands such as "sit" and "down."

6. Greyhounds are afraid of people.
False! Alice loves to get attention from anyone who will give it to her. As a puppy, Alice was trained solely for racing, and was not socialized with people as care givers. When she first arrived in our home, she had to learn about affection and love; now she can't get enough of it! Alice is a little shy around new people but is slowly coming out of her shell and approaching strangers on her own.

7. Greyhounds cannot climb stairs.
False! Alice is an expert stair climber! Since greyhounds are raised in a kennel environment, they are not exposed to some of the everyday obstacles of home life, such as stairs, glass doors, mirrors, or slick floors. During her stay at the prison, Alice's handlers taught her how to tackle these new tasks with positive reinforcement. Once she was adopted, we had to teach her how to play with toys and play games such as fetch.

8. It is difficult to adopt a retired greyhound.
False! There are several organizations throughout Ohio and the surrounding states trying to find loving homes for these wonderful animals. When adopting Alice, we first searched on the internet to find an organization in our area. We then filled out an application and chose five dogs we thought would fit into our lifestyle from their pictures and bios. Once our application was accepted, we talked with a member of the organization to help pick the perfect dog for us. Three weeks later we brought Alice home! In the following months we were contacted to make sure her transition was going smoothly. So, rush on over to www.teamgreyhound.com for more information on Greyhound adoption.

Welcome Jane Whitt
Next time you're in the office, be sure to say "Hi" to Jane Whitt. After 23 years in the hotel and hospitality industry, Jane decided to pursue her lifelong interest in pets. Since joining the team at East Hilliard Veterinary Services, she has been working mostly in a receptionist position but is also learning to assist "in the back". Helping our technicians will give her the hands-on training she will need as she continues her career change. Jane will be taking the Veterinary Technology course at Columbus State Community College. She has no pets at this time (but we think we can take care of that "problem" very soon).

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