Detection of attenuated wavy fibers in the myocardium of Newfoundlands without clinical or echocardiographic evidence of heart disease

Objectives-To determine whether attenuated wavy fibers may be found in the myocardium of Newfoundlands without clinical or echocardiographic evidence of heart disease. Animals-15 Newfoundlands from a kennel with a known predisposition to dilat ed cardiomyopathy (DCM) and 32 dogs of other breeds that died suddenly or w ere euthanatized for reasons unrelated to heart disease and did not have gr oss postmortem evidence of heart disease. Procedure-Echocardiography was performed on all Newfoundlands on a yearly b asis. Necropsy specimens from all dogs were evaluated for attenuated wavy f ibers (ie, myocardial cells < 6 mu m in diameter with a wavy appearance). R esults-None of the Newfoundlands had clinical signs of heart disease, and r esults of echocardiographic examinations were within reference ranges. Seve n Newfoundlands had histologic evidence of attenuated wavy fibers, whereas attenuated wavy fibers were not found in the remaining 8 Newfoundlands or i n any of the 32 dogs of other breeds. Conclusions and Clinical Relevance-Findings suggest that attenuated wavy fi bers in dogs with a known predisposition for DCM may indicate an early stag e of the disease. However, further studies on a larger number of dogs are n eeded to confirm this hypothesis.