Cardio blog: Dilated Cardiomyopathy
Welcome to cardio blog! In this blog I plan to describe some of the interesting cases of heart disease that we see here at MK Vet Group. My thanks go out to all the owners who have allowed their companions to feature in these blogs. I would like to also thank all owners who show such dedication to allow their pets to lead happy and fulfilled lives whilst suffering from heart disease.
In this first blog I am going to be talking about dilated cardiomyopathy, or DCM for short. This is a disease of the heart muscle which occurs in many large breed dogs. The heart muscle becomes weak, and unfortunately the heart is unable to pump properly. This leads to dilation of the heart and eventually heart failure. DCM is usually seen in large purebred dogs such as Dobermans, Boxers, Great Danes and Irish Wolfhounds. Dogs often present at the vets once heart failure is beginning to develop and may have signs such as fatigue, reduced appetite, weight loss, breathing problems and an irregular heartbeat. Cats can also get DCM, but it is much rarer. It was historically associated with a nutritional deficiency in cats, but cat food is now supplemented to prevent DCM from developing.
A recent study in Dobermans has shown that early treatment with a drug called pimobendan before the onset of symptoms can extend the survival time for dogs with DCM. For this reason we are currently offering a free of charge blood test for a heart blood marker called proBNP. High levels of this marker raise suspicion for heart disease and allow us to pick up early cases before they develop symptoms. We have written to all owners of Dobermans, Boxers, Great Danes and Irish Wolfhounds, who have animals aged over 3 years old to invite them to come in for the blood test.
Here is a lovely photo of G. He is a beautiful 7 year old Great Dane. He was blood tested for proBNP and was found to have very high levels. He was admitted to our hospital for an echocardiogram (a heart ultrasound) and an ECG.
G is a very worried dog at the vets so to minimise his stress we performed his ECG in a quiet room away from any noise. He was perfectly behaved for both his diagnostic procedures, he truly is a gentle giant! The ECG is a simple but very useful test of the heartâ€™s electrical activity. It involves attaching a lead to each of the dog or catâ€™s legs and recording the electrical activity of heart on a special machine. The worst bit is the squirting of a little spirit at the lead attachment sites, which can be quite cold. A tasty treat at this stage usually helps as a distraction. Here is a photo of Gâ€™s ECG trace as seen on the ECG machine. Although it is very fast due to him being worried, it is nice and regular. It is not uncommon for us to detect an irregular rhythm called â€˜atrial fibrillationâ€™, which may require some additional medications to slow the heart rate.
Here is a photo of Gâ€™s ECG trace as it appeared on the ECG machine:
The next stage was to perform a heart ultrasound or echocardiography. We are able to use an ultrasound probe to image the heart in real time. The moving heart can be paused at certain points to allow measurements of the heart to be made. From these measurements as well as a general overall impression of the heart we are able to make a diagnosis of the underlying heart disease and make a treatment plan. We lie the animal down very gently on a specially padded table which allows the ultrasound probe to examine the heart from the underside. This gives a better picture and we find that most animals relax quite nicely during the scan (they have been known to nod off!). If they do become agitated, we use treats or a squeaky toy to distract them.
This is the examination table and ultrasound machine.
This is the echo probe. Itâ€™s quite small to allow it to be able to fit between the animalâ€™s ribs without causing any discomfort.
Gâ€™s heart showed enlargement of both the left atrium and ventricle. The atrium is the top chamber of the heart which receives blood before pumping it into the ventricle. The ventricle pumps the blood around the body. The heart is measured in both the long and short axis. Measurements made of Gâ€™s heart showed its ability to contract was reduced.
This is a short axis (cross section) frozen picture of the left ventricle with a measurement being made. You can see that the inside of the ventricle makes a mushroom shape due to the papillary muscles poking into it. The papillary muscles anchor the valve that sits between the atrium and the ventricle.
Here is a video showing Gâ€™s enlarged left ventricle which is not contracting properly (opens in new window):
After I had discussed Gâ€™s condition with his owner, he was prescribed a medicine which helps to increase the force of contraction of the heart. This medicine is called pimobendan, which is given twice daily on an empty stomach. As his condition progresses, G will probably need to take more medicines to help reduce the accumulation of fluid in his body.
It is a sad fact that the long term prognosis for dogs suffering with DCM is not good and many dogs pass away within a year of starting treatment. However we try to make their quality of life as good as possible after diagnosis and they enjoy every day that is given to them. You canâ€™t meet better patients than dogs and cats. For dogs that are caught earlier in the disease process, like G, starting treatment early can help to extend their life span.
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