Adrenal problems more common in dogs than cats

Theadrenal glands of pets are small organs found just above the kidneys. They help the body to respond when stressed and control sodium, potassium, chloride and other electrolytes. Veterinarians rarely see them on X-rays, and even an ultrasound exam may not show the gland very well. During abdominal surgery weoften do not see them.

The main hormone produced in the adrenal gland is cortisol. The adrenals are part of the endocrine system, and while the physiology is quite complex, pet owners should be aware of the two common malfunctions. A low adrenal function will create a life-threatening condition called Addison’s disease. Conversely, an over-functioning gland will produce excessive cortisol in a more common condition called Cushing’s disease.

A dog with Addison’s disease can show symptoms ranging from vague signs of not acting right all the way to life-threatening shock. Symptoms can be acute or more chronic, with waxing and waning signs of illness. Occasionally an astute veterinarian will suspect Addison’sdisease when clients describe a sick dog that responded to intravenous fluids and then regressed. Certain drugs can also damage the adrenal, and a sudden withdrawal of prednisone can create a crisis.

One of the first dogs I saw with Addison’s disease was Samantha, a standard poodle who was quite depressed but showed only minor blood test abnormalities. Luckily her owners were on their way to Philadelphia, and I referred them to the veterinary school there for the emergency diagnosis. I nowsuspect Addison’s more frequently and test anytime the symptoms are suspicious. Treatment is lifelong and is done with oral medicationor a newer product injected every three or four weeks. Cats rarely have Addison’sdisease.

Cushing’s disease can be caused by an overfunctioning adrenal gland or overproduction of a hormone from the brain that stimulates the gland. A Cushing’s dog will drink and urinate excessively and have a pot belly with thin skin and a poor coat. We also frequently see elevated blood test results. The symptoms and blood test changes are similar to what we would seeif we gave too much prednisone. Veterinarians will monitor older pets, looking for changes in blood test results that indicate Cushing’s and a host of other diseases. Treatmentis with oral medication. Dogs can return to a normal appearance, and symptoms will decrease. Cats can have a primary overfunctioning adrenal althoughthis is not common.

Older pets usually drink and urinate more than normal, and diagnosing the problem frequently requires both urine and blood samples. Differentiating Cushing’s disease from other causes such as diabetes, renal disease and a uterus infection is critical.