Spondylopathy in broilers. Case reports

Pathomorphologial investigation of spondylolisthesis leaded to spondylosis in commercial broiler chicken with posterior paralysis: A case study

Spondylolisthesis known as kinky back syndrome is a deformity of the free sixth thoracic vertebra including enlargement and rotation resulting in posterior paralysis in broiler chicken. Genotype, feeding regimes and environment are involved in occurrence of this congenital anomaly. Spondylolisthesis may result in or happen simultaneously with two other major axial skeleton pathologies including spondylosis and spondylitis as a result of occurrence of degenerative necrobiotic lesions and inflammation of the vertebrae, respectively. This report deals with a male broiler chicken with posterior paralysis in the second week of rearing. After euthanasia, the specimen was evaluated at macroscopic and microscopic levels. Macroscopic findings showed the unilateral enlargement of body and transverse process of sixth thoracic vertebra and downward rotation of the body. The histopathological studies revealed the focal chondronecrosis and degenerative changes in articular facets and cranial process of the vertebra. In conclusion, a diagnosis of spondylolisthesis followed by spondylosis was made based on macroscopic and histopathological findings that to the authors' best knowledge, is the first report in a broiler farm in Iran.

Abnormalities in the axial skeleton of broiler breeding fowl

The spinal region containing caudal notarium, free thoracic vertebra (T6), and cranial synsacrum was collected from 27 male broiler breeding fowl which were about 60 weeks old when killed. In 12 birds minor abnormalities were detected on gross morphological examination, with minimal scoliotic curvature being the most frequent finding. Particular attention was paid to articulations. Radiological and histopathological examination revealed subchondral defects due to articular osteochondrosis in every spine examined. Such lesions must represent the sequelae of disturbed endochondral ossification in younger birds. Many lesions were severe, showed little evidence of repair and contained clefts and marked cartilage necrosis. Clefts were not always associated with osteochondrosis but were also observed in slightly thickened articular cartilage and that judged to be of normal thickness. In this instance clefts occurred in deep regions of articular cartilage at sites which frequently showed chondrocyte and matrix change. The latter are likely to be the primary lesions. It also seems probable that the same anatomical sites are predisposed to cell death/clefts and osteochondrosis. Clefts in adult articular cartilage, unrelated to lesions of osteochondrosis, are more likely to be progressive leading to segmental cartilage detachment and destructive cartilage thinning.

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.

Spontaneous spondylolisthesis in embryonic and adult chick

The incidence of spontaneous avian spondylopathy was maintained between 58 and 66% in the progeny of one flock (Flock A) and less than 40% in the progeny of another (Flock B), by proper selection and breeding for 4 generations. Spondylolisthesis, the major type of spondylopathy present, was observed at the first and sixth vertebral levels. Spondylolisthesis was progressive in nature and consisted of a ventrodorsal rotation of the 1st and/or 6th thoracic vertebrae leading to spinal cord injury and paraplegia or partial crippling in some birds. There was occasionally extensive muscle degeneration and connective tissue proliferation around the distorted vertebrae and the spinous ligaments bridging the defect were stretched and appeared heavier than normal. Spondylopathy was also observed in 20-day chick embryos. Spondylolisthesis was observed in 33% of the embryos examined from Flock A-G2 and the other conditions present consisted of scoliosis and abnormal lordosis and kyphosis. Using a grading scale of +1 (mild) to +3 (severe), all cases of embryonic spondylopathy were graded as +1. The back defects present in Flock B-G2 embryos were entirely due to abnormal kyphosis.