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Enterococcal Spondylitis

Femoral Head Necrosis, Proximal Femoral Degeneration, Bacterial Chondronecrosis

Enterococcal spondylitis (ES), also referred to as bacterial chondronecrosis or femoral head necrosis, is a severe degenerative bone disease affecting commercial broiler chickens worldwide. ES is caused by infection of the free thoracic vertebra (FTV) with pathogenic strains of Enterococcus cecorum. Chickens with existing skeletal disorders, such as osteochondrosis dissecans (OCD) lesions in the FTV are more vulnerable to developing ES. OCD lesions occur usually on the growth plates of long bones, particularly the proximal growth plate of the femur and tibiotarsus, but other bones may also be affected.

Chickens affected by ES show varying degrees of lameness, often along with swollen, inflammed hocks and a characteristic posture known as hock-sitting. The onset of hock-sitting and posterior paresis/paralysis correlates with the development of advanced vertebral osteomyelitis lesions.

ES was first reported in 1972. In 2002, the organism Enterococcus cecorum was isolated from osteomyelitis lesions during an outbreak of lameness in broilers in Scotland and the Netherlands.

Clinical Signs

Swollen, inflamed hocks
Symmetrical limb paralysis


  • History
  • Clinical signs
  • Radiographs
  • Necropsy


Supportive careIsolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken "intensive care unit") with easy access to water and food. Limit stress. Call your veterinarian.
Vitamin D36.6 KIU/kg administered IM, once, also add calcium gluconate and oxytocinK Marx



  • Supplementing diet with Vitamin D3
  • Reduce early growth rate of birds

Scientific References

Age Range

It occurs in 2-10 week old 'broiler' breeds

Risk Factors

  • History of infection with immunosuppressive virus (infectious bursal disease virus, chicken anemia virus, staphyloccus)
  • History of non-infectious bone condition
  • Unbalanced diet
  • Raising chickens on wire flooring - it imposes persistent footing instability and is thought to enhance the development of BCO.
  • Male chickens have a higher risk