As the principal investigator in this project, I absolutely agree that no decisions should be made based on cardiac biomarker (blood test) results alone. The research aims to investigate whether they can be relied on to identify Dobermanns who are healthy and those requiring other investigations to see if they have dilated cardiomyopathy (DCM), or if they have another reason for increased biomarker results.
Until the results are analysed, we cannot say how sensitive or specific sole use of the cardiac biomarkers are (although work by Gerhard Wess suggested that dogs with low NT pro-BNP or Troponin I (much lower than the currently used reference ranges by the labs) were very unlikely to have DCM (so good specificity, but low sensitivity).
The gold standard for screening is still both echocardiography and 24 hour ECG monitoring (Holter), which identify dogs with both forms of cardiomyopathy. It is vital to appreciate that a Dobermann can show the arrhythmia from before any echo changes of structural heart disease, but this is still cardiomyopathy (the dog should not be claimed to be free from DCM). From the published literature, there are reliable criteria to define normal, and DCM affected Dobermanns. But there is a grey zone, where a dog may be labelled as “equivocal” where results are somewhere in between the values considered normal and those considered definitely abnormal.
Even if I, or another cardiologist, identifies a Dobermann with DCM, or an equivocal Dobermann, we would never give breeding advice – this is a decision for breeders and a decision to breed is not just based purely on heart testing results. We also need to remember that a young Dobermann with normal results may not remain normal, so serial testing is required. DCM can develop at any age, but it can never be considered normal; it is not an ageing change.
Watch this space! The cardiac biomarkers may be a useful “pre-screening” tool – but a breeder who is serious about reducing risk of DCM in progeny is urged to serially screen for DCM with both echo and Holter within 12 months of breeding. This is even more important in males, who are potentially responsible for many more progeny than a bitch if widely used. Even more important – if early DCM or arrhythmias are identified in your individual dog, we know medication can make a difference to outcome, and will slow down the progression of the disease or control the arrhythmia. So screening will benefit each individual dog and owner.
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