Do different forms of spondylolisthesis occur in broiler fowls?
Lesions of the axial skeleton were studied in 60 young broiler fowls. Forty of these cases were chosen because they showed neurological signs, whereas the remaining 20 were judged to be clinically normal. Different forms of spondylolisthesis were identified both in normal birds and those with clinical signs. In a proportion of cases there was stenosis of the vertebral foramina of the fourth and sometimes fifth thoracic vertebrae and the affected vertebral bodies appeared tilted on lateral radiographs. In others, affected vertebral bodies were tilted but the vertebral foramen was of uniform dimensions. A further type of spondylolisthesis was frequently identified in which step-like defects between adjacent thoracic vertebrae produced stenosis of the vertebral canal. Physeal osteochondrosis. affecting the end plates of vertebral bodies, was identified in the majority of cases but the significance of such lesions is uncertain. The high incidence of vertebral osteochondrosis in the birds studied docs however indicate the propensity for disturbed bone growth in the vertebrae of young broiler fowls.
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Poultry Department, Roslin Research Station, Agricultural and Food Research Council's Institute for Grassland and Animal Production, Roslin, Midlothian, Scotland.