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 dilated cardiomyopathy
(DCM) and 32 dogs of other breeds that died suddenly
or were euthanatized for reasons unrelated to
heart disease and did not have gross postmortem evidence
of heart disease.
Procedure—Echocardiography was performed on all
Newfoundlands on a yearly basis. Necropsy specimens
from all dogs were evaluated for attenuated
wavy fibers (ie, myocardial cells < 6 µm in diameter
with a wavy appearance).
Results—None of the Newfoundlands had clinical
signs of heart disease, and results of echocardiographic
examinations were within reference ranges. Seven
Newfoundlands had histologic evidence of attenuated
wavy fibers, whereas attenuated wavy fibers were not
found in the remaining 8 Newfoundlands or in any of
the 32 dogs of other breeds.
Conclusions and Clinical Relevance—Findings suggest
that attenuated wavy fibers in dogs with a
known predisposition for DCM may indicate an early
stage of the disease. However, further studies on a
larger number of dogs are needed to confirm this
hypothesis. (Am J Vet Res 2000;61:238-241)