Cushing's Disease and the Cavalier King Charles Spaniel

Cushing's Disease in Cavalier King Charles Spaniels

CavalierHealth.org Copyright © 2004 Blenheim Company Cushing's disease, also known as Cushing's syndrome or hyperadrenocorticism, is prevalent in the Cavalier King Charles Spaniel. It is a serious, genetic disorder which produces excess hormones from the adrenal glands. If not promptly treated, it can lead to life-threatening disorders.

What It Is

The adrenal glands produce hormones which help regulate weight, mineral balance, the structure of connective tissue, some white blood cell production, and skin health. Cushing's disease is caused by either an adrenal cortical tumor (a tumor of the cortisol-producing cells of the adrenal gland) or pituitary tumors (which produce excessive amounts of ACTH -- adrenocorticotrophic hormone), the hormone which causes the adrenal glands to produce cortisol), with the result that an excess of cortisol is released in the Cavalier's body.

Symptoms

Symptoms include excessive drinking (polydipsia) and urination (polyuria), increased appetite (polyphagia), panting, symmetrical hair loss (alopecia), hard, calcified lumps in the skin (calcinosis cutis) and discoloration, lethargy, muscle weakness, and susceptibility to skin and urinary infections. Victims also develop bulging, sagging bellies, due to decreased muscle strength and the redistribution of fat from body storage areas to the abdomen. Left untreated, Cushing's disease can lead to life-threatening disorders such as diabetes, congestive heart failure, and liver and kidney failure, and to chronic problems of hypothyroidism, and infections of the skin, ears, gums, eyes, or bladder.

Diagnosis

Cushing's disease can be diagnosed by laboratory tests of blood and urine, including a urine cortisol/creatinine ratio test, an ACTH stimulation test, and low and high dose dexamethasone suppression tests. Once diagnosed, tests can also determine if it is caused by pituitary gland tumors or an adrenal gland tumor.

Treatment

Surgery can cure an adrenal cortical tumor that has not spread to other areas of the body. However, about half of adrenal tumors are malignant and may have already spread. Pituitary Cushing's disease cannot be cured, but the treatment can prolong the Cavalier's quality of life, but not to increase the lifespan. Drug therapies include lysodren (Mitotane), ketoconazole (Nizoral), anipryl (Deprenyl, Eldepryl, Selegiline), and a relatively new drug from the United Kingdom, vetoryl (Modrenal, Trilostane).

Dogs with Cushing's disease are predisposed to other diseases, such as diabetes mellitus, urinary tract infections, kidney disease, hypertension, and pancreatitis.

Cavaliers diagnosed with Cushing's, or otherwise determined to be pre-disposed to it, should not be bred. Any littermates of breeding stock having Cushing's disease should be taken into consideration. The Canine Inherited Disorders Database (www.upei.ca/~cidd/intro.htm) advises to breed only dogs from families with no history of the disorder. Any Cavalier King Charles Spaniel intended to be bred should be blood tested for Cushing's disease at least annually, the closer the examination to the breeding the better.

Control of Canine Genetic Diseases, Padgett, G.A., Howell Book House 1998, pp. 198-199, 222.