Dealing with Dilated Cardiomyopathy

The first step toward dealing proactively with DCM is to have the heart checked annually by a veterinarian. That checkup should include an electrocardiogram (ECG). The ECG makes an electronic recording of the heart’s action and may detect the presence of arrhythmias. If the ECG indicates the presence of abnormalities, the next step is an echocardiogram. This ultrasound examination of the heart can confirm a possible DCM diagnosis.

The rest of the issues goes on to tell of screening that scientist are beginning to try to develop and articles in Journals that have been published.

I decided to post this now as I said, due to the number of dogs with here in the group lately with diseases that have poor prognosis.

We hear a lot about bloat, but there are many different illnesses out there that we all need to be away of. Just this week we have seen Jeri take Inca to a specialists for an infection from an unknown source, and Smiley taking Sadie to the University of Missouri with a sudden onset of Wobblers, and of course we know that Ben has Cardiomyopathy with the complication of arrhythmia. I felt that we should get these things so everyone can learn about them and help better the bread we have all come to love.

When a Great Dane is diagnosed with dilated Cardiomyopathy, the implication of subsequent abnormalities, such as congestive heart failure, also becomes a concern. Dilated Cardiomyopathy (DCM) is prevalent among giant breed dogs, such as Great Dane. In fact, the breed may be second only to Doberman Pinschers in its vulnerability to this condition. While experts agree that the disease may be hereditary in some breeds, until recently there’s been a question whether that’s also the case with Great Danes.

A preliminary answer to that question comes from research led by Kathryn Meurs, D.V.M., Ph.D., associate professor of cardiovascular medicine at Ohio State University. She and colleagues have analyzed the pedigrees of 43 Great Danes with DCM and determined that – as with other breeds--- the condition is genetically based.

Knowledge of whether DCM in Great Danes is truly hereditary--- and if so, what the culprit gene is and how it’s transmitted----will go a long way toward helping veterinarians diagnose the disease early enough for treatment to have the best chance for success. Such screening also will help breeders eliminate affected lines----and with them, the disease---from their breeding programs.

To understand DCM, it is important to understand how the heart works. The heart is like a house with four rooms, or chambers. In the upper half of the heart are two chambers: the right and left atriums. The lower portion contains the right and left ventricles. These four chambers work together to pump blood through the body. Blood enters the heart at the right atrium, where it is stored briefly before being pumped down into the right ventricle, which in turn pumps blood into the lungs. In the lungs, the blood receives oxygen before flowing back to the heart, this time to the left atrium. The blood stays in the left atrium for a few seconds before being pumped down into the left ventricle. From there, the blood is pumped throughout the rest of the body.

Valves regulate the flow of blood to help the heart work efficiently. These valves, located between the atrium and ventricle on each side of the heart, serve as doors between the two areas. When either atrium fills with blood, the valve between the atrium and the ventricle closes to prevent blood from entering the ventricle prematurely. When the valves opens, the blood passes down to the ventricle: once the blood reaches the ventricle , the valve closes again to prevent the blood from flowing back into the atrium. This movement of blood through the body requires muscle power from the heart, particularly from the left side. In fact, the heart is made of a special type of smooth muscle called myocardium. Thus, the term Dilated Cardiomyopathy literally means “enlarged heart muscle disease” 

A Great Dane’s DCM begins long before the dog shows symptoms. The disease starts when individual heart cells waste away and are replaced by scar tissues. As the condition progress, the accumulated scar tissue causes the heart to lose its capacity to pump blood throughout the body. As the heart’s pumping capacity deteriorates, a Great Dane begins to exhibit classic symptoms of congestive heart failure: coughing, exercise intolerance and weight loss.

These symptoms occur because the scar tissue in the heart reduces the organ’s pumping efficiency. Consequently, the volume of blood and pressure within the heart increases. This increased blood and pressure, combined with the heart’s effort to compensate for lost pumping vigor, causes the organ to enlarge: however, the enlargement doesn’t fully offset the heart’s deteriorating efficiency. Eventually the accumulated blood backs up into the lungs, causing coughing and labored breathing characteristic of heart failure. Without treatment, a dog eventually dies.

Great Danes with DCM also may develop a dangerous complication: a disruption in their heartbeat, called an arrhythmia. These disruptions occur when the scar tissue that the atrophied myocardium disrupts the electrical impulse traveling from the brain to the heart to start each heartbeat. These interruptions generally are expressed as premature ventricular contractions (PVC) or atria fibrillation (AF). With a PVC, the ventricle beats earlier than it should: with an AF, a storm of electrical energy causes the upper chambers of the heart to quiver or vibrate. Either way, aggressive arrhythmias can be fatal unless the heart’s normal rhythm is resumed quickly. 

Right now, there is no cure for DCM. Once symptoms become apparent, treatment focuses on controlling symptoms. Veterinarians dealing with this condition try to achieve two goals: medications such as Lanoxin can improve the heart’s contracting ability, and vasodilators such as Vasotec and Enacard can reduce stress on the heart. To deal with failure, veterinarians rely on diuretics such as Lasix, which help to control the amount of fluid that accumulates in the lungs.

The prognosis for dogs with DCM is generally poor, although Great Danes that receive treatment are know to survive longer than other breeds with the disease, particularly Dobermans. Still the key to helping a Great Dane with DCM is to diagnose the disease before symptoms of heart failure develop or before arrhythmia causes sudden death.