Cushings Disease in Older Dogs

Cushing's disease in older dogs is often missed by the pet owner as its symptoms are often just considered normal signs of old age. Cushing's disease (also called hyperadrenocorticism) is caused by an overproduction of the hormone glucocorticoid. Glucocorticoid is produced in the adrenal gland and functions to regulate carbohydrates, protein and fat metabolism in the body. Cushing's disease is often treatable with oral medications to help regulate the hormone production in the pituitary and adrenal glands.

Cushing's disease can affect either the adrenal gland or pituitary gland. Pituitary-dependent hyperadrenocorticism is the more common type of this disease and involves the overproduction of the hormone that encourages production of cortisol (glucocorticoid). This type of disease is frequently caused by a tumor located within the pituitary gland. Adrenal-based hyperadrenocorticism affects fewer animals and is caused by a tumor located in the adrenal gland; the tumor forces the overproduction of glucocorticoid. Excess production of cortisol results in liver enlargement and relaxing of the abdominal muscles.

As dogs age, they often exhibit the quirky symptoms indicative of an older animal. They sleep more, drink more and seem to need trips to the bathroom more frequently. While these might not seem like symptoms of a disease, they are in fact indicative of Cushing's disease. Increased water consumption and the resulting increased urination are the most commons symptoms of this disease. Increased hunger and a distended abdomen are also signs of the disease. Some dogs exhibit hair loss and skin changes such as thinning of the skin and slow healing. Dogs affected with Cushing's disease might pant frequently and tire easily. The collective symptoms are indicative of an overall inability of the dog's body to regulate hormones in its body.

If you suspect your dog has Cushing's disease, your veterinarian will perform a number of blood tests to check your dog's hormones levels. A proper evaluation of your animal should include a complete blood count (CBC), urinalysis and blood chemistry panel. Your vet will be specifically looking for excess levels of cortisol in the animal's lab results. Other tests could include an ultrasound to evaluate the condition, shape and size of the dog's adrenal glands (located near its kidneys). A Cushing's disease diagnosis should include extended labs and tests as well as documented observations of an animal showing symptoms. Some dogs show a single symptom while others exhibit many. The important thing to consider is that any pet owner considering treatment should work with the vet to make sure a combination of tests results in a correct diagnosis.

Most vets and owners choose to treat Cushing's disease with drug therapy to destroy the cells producing the corticosteroid hormones. This drug is called Lysodren and has very serious side effects. While this treatment if very effective for treating dogs with pituitary-dependent Cushing's disease, your pet must have regular blood-monitoring tests to check its cortisol levels. Some animals may even develop Addison's disease, which is the opposite of Cushing's disease and indicates extremely low levels of cortosteroid hormones. Other drugs are used quite effectively to treat other varieties of this disease as well. Other treatments include surgical removal of the tumors if possible, although pituitary tumors are not removed. Radiation can be used to reduce tumor size, but this treatment course is very expensive. For more information on the variety of treatments for Cushing's disease, see Resources below.

Diagnosing your pet as soon as possible increases the chances of managing Cushing's disease in your older dog. This is a very serious disease that requires constant management and care. There is no absolute cure for this disease, but management can help improve the quality of your pet's life and reduce many of the symptoms.