Heart Disease in Dobermanns by Antonia Baker
Unfortunately, heart disease is a problem in Dobermanns. Often this is referred to as "cardio" or "cardiomyopathy" or "dilated cardiomyopathy (DCM)". "Cardio" simply means heart, "myo" means muscle and "pathy" means disease of. Therefore, cardiomyopathy is disease of the heart muscle. The symptoms that the dog experiences are those that are directly due to the heart not functioning properly.
Dogs that have heart failure usually show the following symptoms in the late stages of the disease:
1. Breathlessness
2. Coughing
3. Poor ability to exercise
4. Sudden collapse
5. Being unable to lie down, or if they do they become breathless or start to cough
6. When they are breathing it sounds like they fluid in their lungs.
These are symptoms that occur when the body is no longer able to compensate for a failing heart. In the final hours, the lungs fill up with fluid and the dog literally drowns. It is horrific and very distressing for the dog as well as the owners if the dog is left to suffer this long.
The symptoms can be explained by the anatomy of the heart and lungs. For our purposes, lets think of the heart as having 2 sides, right and left, and in the middle are the lungs. Blood from the body enters the right side of the heart and is then pumped into the lungs. In the lungs the blood picks up oxygen and flows into the left side of the heart. The left side then pumps oxygenated blood to the body i.e. to muscles and the brain. If the heart does not pump well (i.e. heart failure) blood starts to accumulate in the lungs thus causing breathlessness and coughing. It also means that the heart can no longer pump out enough blood to supply the muscles and brain, especially when the demand for oxygen increases i.e. when the dog is running. Thus, the dog can only run short distances and may collapse.
"Heart failure" is the result of heart disease. There are many different types of heart disease but essentially they all cause the same symptoms. For example, humans often go into heart failure after they have had a heart attack. This is mainly due to the blood vessels that supply the heart being narrowed (due to smoking, high cholesterol and blood pressure) causing part of the heart muscle to die and resulting in the heart not pumping as well as it used to and leading to heart failure. As dogs don't smoke or live off fast food they don’t often experience heart attacks.
The heart problem that is most common in Dobermanns is DCM. In this disease the heart becomes dilated which means that it can no longer pump properly. It is similar to blowing up a party balloon. The first time you blow it up it is hard because the rubber has not been stretched before - this is what a healthy heart is like all the time. If you look a balloon that has been blown up and then had the air let out of it you'll know it does not return to the same shape as before and if you blow it up again its much easier than before. A heart that is affected by DCM is just like that - it is bigger than it should be and it is more floppy.
Exactly what causes DCM in Dobermanns is not fully understood. However, there are theories in regards to inheritance (genetics), infectious, metabolic and nutritional causes. Most researches will agree that there is strong genetic component to the disease i.e. DCM in Dobermanns is inherited. The reason we know this is because "cardio" runs in some lines of Dobermanns. That is, a dog that has DCM will die at an early age and virtually all of the offspring also die at an early age with the symptoms described above.
Why is DCM such a problem in Dobermanns?
Dogs with DCM don't usually develop symptoms until the age of 3 or 4 years and prior to this the dog is completely well. A male dog may already have sired 10 or 20 litters (and thus about 100 puppies) before he develops the disease. Thus potentially, DCM can be spread very far and wide through lines that previously have not been affected. If puppies from this male are then bred (before they die), DCM will continue to be passed on and spread through the breed.
We know that heart disease in Dobermanns is inherited and genetic test is currently being developed in the US. The problem is that it appears that there are lots of genes that are responsible for causing heart disease. It is not a simple matter of just looking at one gene and if it is mutated than the dog will die of DCM. The current research shows that there may be as many a 20 genes that cause DCM. The future genetic test may involve looking at several genes that if mutated are likely to cause DCM in that particular dog.
What does this mean for the average Dobermann owner?
Firstly, prevention is better than cure (as there is no cure). Before buying a new puppy do your research. Try to find out if the Dobes in the lines are still alive and if not what age they died at and why. If a particular line of Dobes all die suddenly at a young age, DCM may be a problem.
Secondly, ask the breeder if both parents have had cardiac ultrasounds, which currently, is the best test that we have. An ultrasound looks at the way the heart contracts, the size of the heart chambers, the valves and can also work out with what sort of pressure the heart is pumping (ejection fraction). Unfortunately, this ultrasound only tells us that at the time of the test the dog did or didn’t have changes in the heart consistent with DCM. This does NOT mean that the same dog won’t develop DCM later in life. Thus, these ultrasounds need to be done on a yearly basis.
Ultimately, the diagnosis of DCM is a tissue diagnosis. This means that a sample of heart muscle is analysed under the microscope. As very few owners are willing to put their dogs through a heart biopsy when they are alive and the diagnosis is almost exclusively made at the time of autopsy.
So why bother doing an ultrasound at all? Lots of reasons. Firstly, if the ultrasound is suggestive of DCM the dog should not be bred as it is likely that it will be passed onto the puppies. Secondly, if detected early enough, the dog can be started on medication to help strengthen the heart, prolong life and ease the symptoms of heart failure.
People will try convince potential buyers that 6 or 7 years is the life expectancy of a Dobermann. If you go to Europe there are quite a few Dobes that are still competing in obedience and agility/Schutzhund and they are 10+ years. Your Dobe should live to 10 years at the very least. Therefore, when buying a new puppy, look at the grandparents, great grandparents and beyond. If there is a history of dogs dieing at an early age for no apparent cause be very cautious. If the all the dogs live to 13 years and beyond you can be almost certain that DCM is not a problem.
Hopefully, a genetic test will be available soon. This would allow breeders to test their dogs prior to mating. It would also allow owners to test their dog and accurately predict if DCM will be problem. Potentially, this test could help to eradicate DCM from the breed.
In Perth, there are several specialist veterinarians that can perform cardiac ultrasounds.
References
1. Influence of antiarrhythmia therapy on survival times of 19 clinically healthy doberman pinschers with dilated cardiomyopathy that experienced syncope, ventricu;ar tachycardia, and sudden death (1985-1998). CA Clavert, J Brown, Journal of American Animal Hospital Association, 2004 Jan-Feb, 40(1):24-8.
2. A double Blind, randomized, placebo-controlled study of pimobendan in dogs with dilated cardiomyopathy. VL Fuentes et al. Journal of Veterinary Internal Medicine, 2002 May-Jun, 16(3):255-61.
3. Effect of severity of myocardial failure on heart rate variability in Doberman pinschers with and without echocardiographic evidence of dilated cardiomyopathy. Journal of the American Veterinary Medicine Association, 2001 219(8):1084-8
4. Canine idiopathic dilated cardiomyopathy. Part I: Aetiology, clinical characteristics, epidemiology and pathology. A Tidholm et al Veterinary Journal 2001 162(2):92-107.
5. Evaluation of the cardiac actin gene in Doberman Pinschers with dilated cardiomyopathy. KM Meurs et al. American Journal of Veterinarian Research. 2001, 62(1):33-6.
6. Use of western immunoblot for evaluation of myocardial dystrophin, alpha-sarcoglycan, and beta-dystroglycan in dogs with idiopathic dilated cardiomyopathy. AW Spier et al. American Journal of Veterinarian Research. 2001 62(1):67-71.