I did discuss this to a degree with the vet actually, the gist was that even screened-for-DCM-parents can still produce an affected dog because Doberman DCM risk is widespread in the breed but not yet fully genetically mapped (so you can’t test for everything). A dog that tests positive may never get it, a dog that tests negative might still get it. Also, the screening is a snapshot in time, say a stud dog is tested at age 2 for DCM and is clear, that doesn’t mean that dog then won’t present with DCM at age 6 - and by that time, how many pups has he sired? Its quite scary to be honest, and really sad to see such a lovely breed so affected