A case of vertebral and rib malformation with a short neck in a Holstein calf

Abstract

　A 7-day-old Holstein calf was presented to the Nihon University Animal Medical Center for evaluation of congenital shortening of the neck. At presentation, the calf was generally in good condition with no neurological signs. Hematological and serum biochemical values were largely unremarkable. Computed tomography showed atlanto-axial fusion due to failure of division at the odontoid process, fusion of the fourth and fifth cervical vertebrae and fusion of the seventh cervical vertebra with the first and second thoracic vertebrae. There were 13 ribs on the left side, and 12 ribs on the right side. Some thoracic spinous processes were also fused. Furthermore, the vertebral bodies were bent ventrally from the third to fifth thoracic vertebrae. In the lumbar region, the left transverse process of the first lumbar vertebra was absent, and fusion of the first and second lumbar vertebrae was found. The third lumbar vertebral body was wedge shaped, and the third and fourth lumbar vertebrae were fused and curved dorsally. Pathological examination revealed a bony protrusion in the ventral side of the spinal canal at the third and fourth cervical vertebrae. No abnormalities were found in the brain or spinal cord. Virus isolation and genotype testing were negative. Thus, the cause of congenital vertebral and rib malformation was inconclusive. However, multiple vertebral deformities suggested a morphogenetic disorder during somite formation in early embryogenesis.