I find myself in a bit a quandary. My dog, Apollo, is a boxer, a breed that is predisposed to a type of heart disease called dilated cardiomyopathy (DCM).

Dilated cardiomyopathy is a disease of the heart muscle. At its most basic level, the heart becomes weak and can no longer adequately pump blood throughout the body. Most frequently, the part of the heart (the left ventricle) responsible for pumping oxygenated blood throughout the body is affected, but sometimes the right ventricle that receives blood from the body and pumps it to the lungs is involved, either in addition to or instead of the left ventricle. The symptoms of dilated cardiomyopathy can include weakness, exercise intolerance, coughing, difficulty breathing, and, if the right ventricle is affected, a fluid-distended abdomen.

My quandary involves whether or not to screen Apollo for the disease. Based on his general demeanor and a physical exam, he appears to be healthy, but he could be in what is called the “preclinical” stage of the disease. DCM is progressive — in other words, it worsens over time. Dogs that are “preclinical” do not yet have symptoms of the disease, but evidence of its existence can be picked up with advanced diagnostic tests, in this case an echocardiogram.

So far, I have decided not to schedule Apollo for an echo. My reasoning is based on the fact that there is some truth in the adage “ignorance is bliss.” Also, the evidence for giving dogs with DCM medications before they have developed congestive heart failure has been fairly sketchy. Some doctors have been recommending ACE inhibitors, but I haven’t found the science behind their use under these particular circumstances to be especially compelling. Things might be changing with the arrival of pimobendan, however.

Pimobendan is the new “it” drug in cardiology. It has been used for quite a long time in Europe but is a relatively new arrival on the U.S. veterinary scene. Pimobendan is a positive inotrope, a type of medicine that increases the strength of muscular contractions of the heart. You can probably see how this could potentially be beneficial in cases of DCM. A study that looked at the use of pimobendan for preclinical DCM in Dobermans showed that the drug “prolongs the time to the onset of clinical signs and extends survival.” On average, the dogs in the study that got pimobendan lived for 623 days in comparison to 466 days for those that did not.

Now Boxers are not Dobermans (the diseases are not identical in the two breeds), so I’m not going to rush and schedule that echo for Apollo quite yet, but I’m going to be keeping an eye out for any more studies that support the use of pimobendan in cases of preclinical DCM.

 

Dr. Jennifer Coates

Reference

Efficacy of pimobendan in the prevention of congestive heart failure or sudden death in Doberman Pinschers with preclinical dilated cardiomyopathy (the PROTECT Study). Summerfield NJ, Boswood A, O'Grady MR, Gordon SG, Dukes-McEwan J, Oyama MA, Smith S, Patteson M, French AT, Culshaw GJ, Braz-Ruivo L, Estrada A, O'Sullivan ML, Loureiro J, Willis R, Watson P. J Vet Intern Med. 2012 Nov-Dec;26(6):1337-49

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