In the Doberman, it is primarily a genetic trait which results in an inability of the heart to contract normally which leads to abnormal heart function. To compensate for the heart's poor contractile ability, the heart dilates increasing the chamber size which, in the early stages of the disease, will improve output of the heart (stroke volume). At this time the disease is asymptomatic. With further progression of the disease, there will eventually come a time when further dilation of the heart no longer improves stroke volume but, in fact, leads to increasing pressure within the heart. This, in turn, causes a backing up of blood in the blood vessels and lungs which causes fluid to leak out into the lungs leading to difficulty breathing and, eventually, death.

    Symptoms and progression vary widely. Some dogs will have no visible symptoms and yet die without warning. We are seeing this more and more in dogs as young as 3 years. Other dogs will display heavy breathing, wheezing, coughing, loss of energy and appetite. The condition is not curable although diuretics and other medications can provide some measure of comfort for the dog.