Acute pectoral myopathy in broiler breeders.

An acute myopathy is described which principally affects the superficial pectoral muscle (Musculus pectoralis) of broiler breeders between 12 and 20 weeks of age. The disease is sporadic and associated with rapid death. The lesion is characterised histologically by a severe my o degeneration but with little or no cellular response. The cause is unknown.