A cardiomyopathy ("sudden death syndrome") of adult hens.

The lesions associated with a syndrome of sudden death in adult hens is described. The syndrome occurred primarily in broiler-breeder hens and in three flocks of commercial egg-laying strains. All flocks were housed on deep litter. Deaths occurred from 24 to 26 weeks of age until approximately 30 weeks of age. Congestion and oedema of viscera occurred consistently and concentric or eccentric myocardial hypertrophy associated with left atrial endocardial fibroelastosis occurred in many birds. The cause of the syndrome has not been determined. The findings of cardiac failure, myocardial hypertrophy and the lack of cause or distinct myocardial lesions qualifies this syndrome as a cardiomyopathy.