Dilated cardiomyopathy in Dobermann
This test is for all four DCM variants: DCM1, DCM2, DCM3, and DCM4
Dilated cardiomyopathy is an inherited heart disease affecting the Doberman breed. The disease is characterised by dilation of the ventricles leading to progressive thinning of the wall and irregular heartbeat as well as enlargement of the ventricle, which decrease the overall heart function and output. Insufficient blood circulation can lead to build up of fluid in the lungs and other parts of the body. Affected dogs can show progressive deterioration leading to death or can be relatively asymptomatic and then die suddenly.
Dilated cardiomyopathy is a widespread inheritable disease in Doberman. Affected dogs suffer from congestive heart failure or sudden cardiac death. Ventricular tachyarrhythmia is a typical sign of DCM and can be diagnosed by an echocardiogram or electrocardiogram (ECG). Pedigree analysis indicates an autosomal dominant mode of inheritance.
Four genetic variants have been identified to be associated with dilated cardiomyopathy: the DCM1 variant located in the PDK4 gene (provides energy to the heart) and the DCM2 variant located in the titin (TITIN) gene (helps the heart to contract). Recently DCM3 and DCM4 have been identified.
Please note that all four variants are risk factors, which means that they increase the risk of DCM but doesn’t necessarily mean that dogs tested positive will always develop the disease as there are other factors, genetic and non-genetic, which can influence the disease.
DCM1 and DCM2
The mode of Inheritance in DCM1 and DCM2 is dominant with variable penetrance, which means that genetically affected dogs may also show very mild or even no symptoms during their lifetime.
- Dogs carrying the DCM1 variant (alone) heterozygous or homozygous, are 10 times more likely to develop the disease than dogs without the variant, 37% of the dogs with this variant will develop the disease.
- Dogs carrying the DCM2 variant are 21 times more likely to develop the disease, 50% of the dogs with this variant will develop the disease.
- Dogs carrying both variants have the highest risk to develop DCM (30 times) and 60% of the dogs with both variants show symptoms. These dogs should be monitored regularly for signs of the disease so that medication could be provided if needed to slow down the progression of DCM.
DCM3 and DCM4
DCM3 is linked to lower overall risk, but it follows a dominant inheritance pattern, which means that the risk of developing the disease is increased if the dog has one or two copies of the risk variant; whereas DCM4, on the other hand, is linked to a higher risk of developing DCM, but it follows a recessive inheritance pattern, and therefore the risk is high only in dogs carrying two copies of the risk variant DCM4 in the absence of DCM3.
In addition to the genetic factor, other factors including nutrition, exercise level and other genes can contribute towards increasing the risk of developing the disease. And therefore, the genetic test helps to identify the DCM variants, however, a proportion of genetically affected dogs may not develop the disease or show any of its symptoms. Moreover, there maybe other, yet unidentified, variants which can cause DCM in this breed and so even if a dog is tested clear for all variants, regular clinical testing at the vet is still recommended.