Iatrogenic fractures of ribs and vertebrae during delivery in perinatally dying calves: 235 cases (1978-1988).

To determine the pathogenesis of vertebral fractures in calves during the perinatal period, a retrospective study was done to determine the relationships between clinical factors at dystocia and the findings during necropsy of 235 perinatally dying calves. It was concluded that excessive traction is the most important cause of rib and vertebral fractures in the calf during dystocia. Vertebral fractures in perinatally dying calves may not be simply judged as a sign of asphyxia. The occurrence of vertebral fractures is highly correlated with the type of delivery and the force of traction. The veterinarian as well as the type of calf also are influencing factors. More perinatally dying calves were delivered after hips were locked, when extraction had been forced, or through induction of trauma when the head of the calf had the pelvic canal during the first obstetric examination. Consequently, fetal position at delivery may predispose calves to risky extractions and to the risk of perinatal death secondary to trauma. In light calves, significantly more vertebral fractures occurred during extractions than in other calves. Therefore, the veterinarian should accurately estimate the birth weight of the calf and the force of traction that should be applied.