Cardiomyopathy in dogs

Overview

The term cardiomyopathy literally means "sick heart muscle." Of the three types of cardiomyopathy, the type most commonly seen in dogs is Dilated Cardiomyopathy (DCM). Dilated means the heart becomes larger; the increase in size is due to the size of the heart chambers. When the heart chambers become larger, the muscles that form the walls of the heart stretch thinner.  They also become unable to contract with normal strength, reducing the pumping capacity of the heart. This decreased ability of the heart to function affects the lungs, liver, and other systems in the body, and usually leads to congestive heart failure.

Dilated Cardiomyopathy is most commonly seen in large and giant breed dogs (over 50 pounds), and is rarely found in small dogs and toy breeds. Doberman Pincers and Boxers have the highest incidences by breed, with growing numbers of Cocker Spaniels being diagnosed. Most dogs are two to five years of age at the onset of symptoms, with male dogs diagnosed slightly more often than females. In most cases the cause of DCM is unknown, but there is strong evidence of genetic predisposition.

Symptoms

• Tires easily
• Weight loss
• Lethargy
• Rapid breathing, frequently with cough
• Edema, particularly in the abdominal area
• Fainting

Prevention

Dilated cardiomyopathy develops over many months or even years - early treatment can ease symptoms and prolong life. Regular veterinary exams and screening for early signs of heart abnormalities can include: chest x-rays, ultrasound imaging, electrocardiogram, echocardiography, and ambulatory electrocardiograph (Holter monitoring).

Treatment

Treatment involves diet, appropriate exercise, and medications to increase heart function and prevent cardiac arrhythmias. Nutritional support may involve low-salt diets and/or supplementing with l-carnitine or taurine. A diuretic may be prescribed to remove excess fluid build up in the chest cavity and abdomen. Drugs, such as Digoxin, Cardoxin, Lanoxin, and ACE inhibitors may be used to stabilize and support the failing heart as well as to control the arrhythmias.

By the time dogs show symptoms of dilated cardiomyopathy and congestive heart failure, they rarely live beyond a year. The long-term outlook for dogs with DCM is usually quite poor. Despite this, many dogs with DCM can benefit from medical treatment that helps control symptoms.

References:

Canine Inherited Disorders Database. (1998) <http://www.upei.ca/cidd/Diseases/cardiovascular%20diseases/cardiomyopathy.htm> (26 February 2008).

Carlson, Lisa D, D.V.M., and Giffin, James M., MD. Dog Owner's Home Veterinary Handbook. New York:  Howell Book House, 2000.

Hines, Ron, DVM, PhD. Heart Failure In Dogs I, Canine Dilated Cardiomyopathy. 6/24/06. <http://www.2ndchance.info/dogdilcardiomyopathy.htm>  (26 February 2008).

Meurs, Kathryn M., DVM, PhD. CANINE DILATED CARDIOMYOPATHY
INSIGHTS INTO DIAGNOSIS AND MANGEMENT. (presented at The North American Veterinary Conference 2005 Proceedings.) <http://www.ivis.org/proceedings/navc/2005/SAE/044.pdf?LA=1> (26 February 2008).

Montoya, J. Alberto, DVM, PhD, Dilated cardiomyopathy in dogs. <http://www.vin.com/proceedings/Proceedings.plx?CID=WSAVA2002&PID=2530> (26 February 2008).