My Pet Has DCM. What Does That Mean?

DCM is Dilated Cardiomyopathy. It is a disease that causes the heart muscle to gradually get weaker and weaker. The inability of the heart to squeeze blood out well causes problems as the disease progresses.

Normal vs. DCM hearts

How does this happen?

​True DCM seems to be coded in the genetics of our beloved pets. The breeds that are diagnosed most commonly with DCM are large breeds including, Great Danes, Newfoundlands, and Irish wolfhounds. The top two however, are Boxers and Dobermans.

DCM shows itself in two phases

The Holtor monitor: the brains of the unit

PHASE ONE:
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The first phase is occult DCM. Occult DCM is suspected when the patient presents to their cardiologist with evidence of heart disease. Perhaps your regular vet heard a new heart murmur or caught arrhythmias. An arrhythmia is when the nice steady heartbeats are interrupted by part of the heart beating out of sync. If this happens too frequently, it can be life threatening. The cardiologist may put your dog on medication for both arrhythmias and medication to add power to the “squeezing” ability of the heart. Typically, in the occult phase, the need for medication varies from pet to pet, therefore the care of a cardiologist is most ideal. 

If the arrhythmias are frequent, or your pet is having syncopal episodes, your vet or the cardiologist may suggest a Holter monitor. A Holter monitor is a small box attached to your pet with little stickers to hold pads onto their skin. A recording of an electrocardiogram (ECG) is done for 24 hours (typically) and then analyzed for life-threatening arrhythmias. ​

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Applying the sensors for the Holter monitor

The bandage keeping the Holter monitor in place during the prescribed time by the cardiologist

Syncopal episodes are fainting or collapse episodes that happen. They are rightfully terrifying and it is this author’s hope you never need to witness this in your pet.  What is usually happening, is that the arrhythmias happen at such a fast rate that blood doesn’t have time to fill the heart so the blood cannot be pumped out of the heart. This results in the brain (and rest of the body) not getting adequate oxygen and therefore they pass out. BUT, the heart could also pause for a long period. This has the same outcome of no blood being pumped to the brain causing your pet to pass out, or faint. To be sure the correct issue is being treated, a Holter recording is so valuable.

PHASE TWO:

The next phase of DCM is just called “DCM”. This is officially diagnosed by the cardiologist based on measurements he/ she acquires during the echocardiogram. If your pet is diagnosed with DCM, your pet will undoubtedly be put on many medications. These medications will help your pets heart use the strength it has in the heart muscle more efficiently, and relax the blood vessels outside the heart so the heart doesn’t have a hard time pumping the blood out to the tissues of the rest of the body. The goal during this phase, is to slow the progression of the disease. As of now, there is no cure. **For True DCM** As the disease progresses, the veterinarian will add more therapies to avoid congestive heart failure.

Below are images from an echocardiogram showing the amount of squeezing a normal heart and a DCM heart is doing. The right shows a normal heart. The two grey areas are the walls of the heart and the black between them is the open space inside of the ventricles. When the heart is squeezing the gap should be very small as in the right image. With a heart that has DCM, the heart does not squeeze and the gap between barely changes as in the picture on the left.

An echocardiogram showing a normal dog heart squeezing

An echocardiogram showing a dog with DCM trying to squeeze

Congestive heart failure results from advanced heart disease.  The heart cycles blood through from the lungs into the top chamber of the heart called the left atrium. The blood then goes through the mitral valve into the left ventricle. From the left ventricle, its gets pumped out into the body with nice fresh oxygen it picked up from the lungs. 
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When DCM is advanced, the left ventricle has lost the strength to squeeze the blood out to the body, as a result the blood stays in the ventricle. When there is blood in the ventricle, the heart can not add blood from the atrium. When the blood can’t leave the atrium, the atrium stretches to attempt to accommodate a larger volume. When the left atrium has stretched and can’t fit more blood from the lungs, the blood backs up into the lungs. This increases the pressure in the lungs and the lungs fill with fluid. The fluid in the lungs is congestive heart failure. This can be controlled with medications as well but when they have been in heart failure once, it will recur. 

​Is there any good news with this terrible disease?!

There is a little silver lining. Sometimes, DCM is diagnosed because of poor nutrition. A diet deficient in taurine or carnitine can have detrimental effects on the heart muscle resulting in a diagnosis of DCM. It is the author’s opinion that this is misleading since in these cases the weaker heart or Systolic failure, can be reversed with adequate diet changes, whereas true DCM cannot be reversed. 

There is a connection between boutique, exotic, and/or grain free diets (BEG diets). Cummings School of Veterinary Medicine at Tufts University and U. C. Davis School of Veterinary Medicine are working with the FDA to uncover what the connection is between these types of diets and weak hearts. Read our article about grain free foods here.

If your vet is concerned that the diagnosis of DCM results from the food your pet is on, they might suggest a blood test called a pro-BNP or a Taurine level.  Abnormal results many indicate the need for a further workup by a cardiologist. But to be clear, a normal test result does not mean that there isn’t a problem. 

The gold standard test for diagnosing DCM is an echocardiogram. As this is often cost prohibitive, changing the diet for your pet is not a bad idea. There are diets that have not been associated with any reports of DCM, your vet should be able to guide you here. 

If your pet has been diagnosed with DCM, it is a difficult diagnosis to hear. But understand, your pet doesn’t know they are sick. They may feel tired as the disease progresses but there is no pain with this disease. Don’t restrict their activity, let them play and treat them as they have always been treated. Enjoy every moment. 
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Also, ask your vet for written scripts for their medications. With few exceptions, human pharmacies carry most of the medications prescribed for DCM and are inexpensive. Check out ourpage about different pharmacies and where you can get your pet's medications here.

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We hope this article helps you understand what dilated cardiomyopathy is and how to diagnose it. Below are some resources for this article. Let us know what you think in the comments below.

Sources:

1.  Journal of the American Veterinary Medical Association December 1, 2018, Vol. 253, No. 11, Pages 1390-1394

2. Cardiology for Veterinary technicians and Nurses. Durham Jr., H. E. 2017. Wiley. pp. 279-283 
If you'd like to purchase a copy here is a link: ​https://imfpp.org/cardio4vettech

Guest Author

Kristie Garcia LVT VTS (Cardiology)

After graduating and passing the VTNE in 2001, Kristie worked in GP for 3 years before starting at Garden State Veterinary Specialists (GSVS) in NJ. Later, after working for a few years to work in the Cardiology Department at Cornell University Hospital for Animals, she returned to GSVS to work in the Cardiology department in 2007. She achieved her VTS for Cardiology in 2009. She very much enjoys all things about Cardio and strives to make those around her love it as well, or, at least be more at ease with it. She is currently the Director at Large for the AIMVT Cardiology technicians. When she isn’t writing or talking about Cardiology, she is raising 3 kids with her patient husband,  2 dogs, 1 gecko and rooster and a fish. You can contact Kristie here.

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