Congenital Cardiomyopathy Associated to Curly Hair in Polled Hereford Calves in Uruguay

Abstract

A cardiomyopathy associated with a woolly hair coat (CWH) in calves of the Polled Hereford breed is described for the first time in Uruguay. The disease was diagnosed in a stud farm (70 cows) and in a commercial farm (80 cows), both with  purebred Polled Hereford cows. A pedigree Polled Hereford bull, of different blood lines, was used in both farms. Four affected calves were born in 1996 in the stud-farm (5,71%) and 3 in the commercial farm in 2009 (3.75%). Analysis of the pedigrees in the stud-farm demonstrated common ancestors for all sires and dams of affected calves. CWH calves presented at birth a tight, curly hair coat and showed clinical signs of depression and exercise intolerance. Most calves died within 7 days of birth. Postmortem examination in 4 euthanized calves showed a marked cardiomegaly characterized by increased cardiac weight (mean 391.3 g ± 60 SEM) and cardiac weight / birth weight ratio (mean 1.178% ± 0.131). All calves had massive bi-ventricular and septum hypertrophy with severe reduction in ventricular chamber volume. Microscopically, there was myocyte hypertrophy, haphazard disarray of bundles of myocytes, and slight interstitial fibrosis. The woolly skin had severe folicular dysplasia with distorted hair follicles, abnormal inner root sheet, and hook shaped hair bulbs. It is concluded that CWH occurs with relatively high incidence in the Polled Hereford breed in Uruguay. CWH phenotype is unique, pathologically different to human (Naxos and Carvajal diseases) and murine (waved 3) cardiocutaneous syndromes.