Bacterial Chondronecrosis with Osteomyelitis (BCO) in Broiler Chickens: Bacterial Causes, Pathophysiology and Control, with a Focus on the Potential of Electron Beam-Inactivated Vaccines

Bacterial chondronecrosis with osteomyelitis (BCO) is a major cause of lameness in modern broiler chickens. It remains a persistent challenge in the broiler industry, resulting in substantial economic losses and serious animal health concerns. The pathogenesis of BCO involves rapid muscle growth, resulting in disproportionate body weight relative to skeletal maturity, thereby increasing mechanical stress and leading to microfractures and osteochondrotic clefts in the proximal growth plates of the femora and tibiae. Infection progresses via hematogenous dissemination and colonization of the leg bones by opportunistic pathogens, primarily Staphylococcus spp., Enterococcus spp., and Escherichia coli, originating from the gastrointestinal or respiratory tract, leading to chronic inflammation, ischemia, biofilm formation, and progressive bone necrosis. Control strategies, including selective breeding, enhanced management and production practices, nutritional interventions, and the administration of antimicrobial agents, offer partial mitigation but have failed to provide a permanent solution to BCO incidence. Vaccination is one of the most promising and targeted immunological approaches to enhance the host immune responses against bacterial pathogens. Electron beam (eBeam) inactivated vaccines represent a significant advancement among available vaccination strategies. This review leverages current knowledge of the etiology, pathophysiology, control measures, and the use of eBeam technology (EBT) in vaccine development to provide a scientifically grounded and innovative approach to controlling BCO-associated lameness in broiler chickens. This article also provides insights into future directions for integrated, antibiotic-free strategies to mitigate BCO and revenue losses, enhance broiler welfare, ensure consumer safety, and support the long-term sustainability of the global poultry industry.