Enterococcal-related vertebral osteoarthritis in South African broiler breeders: A case report

Infections in broilers and broiler breeders by Enterococcus cecorum, causing clinical disease, have increasingly been described in various countries in the Northern Hemisphere over the past decade. This case report describes an outbreak of enterococcal-associated vertebral osteoarthritis (EVOA) in male broiler breeders in several flocks in South Africa. Male birds aged 4 and 9 weeks displayed the common presentation of lameness, paresis or complete paralysis. Autopsies of culled birds revealed masses on caudal thoracic vertebrae T5-T7, with vertebral osteomyelitis and spondylitis. Microbiological assays identified E. cecorum cultured from spondylitic lesions. Affected flocks were treated with amoxycillin at 25 mg/kg in the drinking water for 5 days, resulting in decreased numbers of lame birds and culls. The origin and pathogenesis of EVOA are poorly understood, which limits prevention to environmental factors that may inhibit systemic access by the enteric bacteria. Skeletal growth trends of male birds are thought to increase their susceptibility to bacterial colonisation at sites of skeletal strain, resulting in abscesses and lesions. Evidence points to the emergence of E. cecorum strains with increased pathogenicity; this highlights the need for greater understanding of the origins, treatment and prevention of EVOA to minimise its economic impact on poultry operations.