Cushing’s Disease In Dogs

Cushing’s disease – hyperfunction of the adrenal cortex in dogs

Definition

Cushing’s disease, named after Harvey Williams Cushing, is a disease in which there is increased stimulation of the adrenal cortex and, as a result, excessive cortisol production. The symptoms are known as Cushing’s syndrome (hypercortisolism, “too much cortisol”).

The adrenal glands are pea-sized organs located right next to the kidneys.

Causes

In most cases (80-85%) the cause is a small benign tumor in the pituitary gland. This tumor constantly sends an excess of a signal (the hormone ACTH) to the adrenal glands, causing them to produce cortisol and release it into the bloodstream. The adrenal glands get bigger and constantly produce too much cortisol.

In rarer cases (15 – 20%), the cause is a small tumor in one of the adrenal glands, which itself produces and releases cortisol.

Too high a cortisol concentration in the body can also be caused by too high a dose of medication (“cortisone”).

Symptoms

Most dogs with Cushing’s disease drink heavily and urinate excessively. Many are constantly hungry, are less keen to move, and get a sagging belly. Skin changes can often be observed: thin, dull fur up to complete hair loss, dry, wrinkled, scaly skin with comedones (blackheads) and as a complication purulent skin inflammation and hair follicle mite infestation.

The most commonly affected are small, older dogs and the boxer, poodle, and dachshund breeds.

Diagnosis

If Cushing’s disease is suspected, the veterinarian can first carry out a general blood test and, if necessary, an ultrasound examination of the abdominal cavity and a urine test. Then blood is taken twice at an interval of one hour and the hormone ACTH is injected in between. A comparison of these two blood values ​​confirms the suspicion of over-or underproduction of cortisol but says nothing about the cause. For this, the amount of ACTH in the blood must be measured before the injection.

Therapy

The therapy differs depending on the cause of the disease. In the case of drug-related excess cortisol, the medication must be readjusted.

If a pituitary tumor (tumor in the pituitary gland) is the cause, a drug is given that reduces the production of cortisol in the adrenal glands. It has to be given for life and is very effective, although it takes several weeks for the symptoms to disappear. The dose must be checked at regular intervals by the veterinarian.

A tumor of the adrenal gland itself can be treated with the same drug or surgically removed.