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Dilated Cardiomyopathy

Dilated Cardiomyopathy (DCM) is a disease of the heart muscle in which the walls of one or
both ventricles become weak. This results in an enlarged heart, which can no longer pump
blood efficiently.

DCM is more common in large breed dogs – commonly Dobermann Pinschers, Great Danes,
Irish Wolfhounds and Newfoundlands – and some medium sized breeds, such as Cocker

DCM is an adult onset disease in most cases – often diagnosed at around 5-7 years of age.

What causes DCM?

The mechanism behind DCM is not fully understood. It is known to be inherited in several breeds; but it can also be linked to certain infectious diseases, dietary deficiencies, and low thyroid hormone levels, amongst other issues.


Diagnosis of DCM consists of (1) Echocardiography (ultrasound of the heart) to look for structural changes, and (2) ECG or Holter monitoring to look for arrhythmias. Sometimes other tests such as chest radiographs or blood tests will also be recommended, to help determine the best treatment options.

Clinical Signs and Stages of Disease:

1. “Occult Stage”: This is the early stage of DCM, when the heart becomes dilated, but outwardly, no clinical signs are evident. Your dog will seem perfectly healthy at this stage, and evidence of disease will only be seen if tests are done. This stage is long and often lasts 2-4 years.
2. “Overt Stage”: This is when heart failure develops. Clinical signs will now be evident e.g. breathing difficulties, lethargy and/or collapsing. This stage may last only weeks or months before deterioration occurs.


If occult/early DCM has been diagnosed, yearly examinations are recommended; including an echo and ECG monitoring. It is also recommended that owners monitor Sleeping Respiratory Rate once weekly at home. This is an easy and reliable way to detect progression of the disease. (While your dog is asleep count the number of breaths taken in 60 seconds. Values above 30 suggest the presence of heart failure.) In the overt stage of DCM, regular examinations will be necessary to appropriately manage the condition. This will involve a physical exam and may also include echo, ECG or blood tests at regular intervals initially. Your vet can advise on how often you will need to revisit.


In the occult/early stage, there may be several years in which no external signs of disease are perceived. A small number of dogs can die suddenly during this stage without ever showing clinical signs - this is more common in the Dobermann breed.

Once the overt stage is reached, extra medications will be needed to control your dog’s clinical
signs. Depending on response to therapy, some dogs may cope very well with the disease for several weeks or months. This varies with each case and may be difficult to predict. Sudden death is also possible during this stage, especially in the Dobermann.

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