Large offspring syndrome? : perinatal medical management of a valuable embryo transfer calf

Abstract

A Holstein heifer, carrying a valuable embryo transfer calf, presented with suspected hydrops, seven days prior to her expected parturition date. Examination revealed severe hydoallantois and a live calf with a normal heart rate. Fetal maturation and parturition were induced, and a healthy female calf was delivered by uncomplicated Cesarean section 24 hours later. The calf displayed several characteristics associated with Large Offspring Syndrome, including fetal edema (mild), large birthweight, persistent tachypnea, and large umbilical vessels. Large Offspring Syndrome is frequently attributed to techniques of nuclear transfer, in vitro fertilization, and less commonly, multiple ovulation embryo transfer. Despite intensive research, abnormal phenotypes have not been conclusively linked to specific genes or pathophysiology. However, Large Offspring Syndrome can be repeatably produced under certain conditions of the embryonic or uterine environment. In this case, the details of the farm breeding program are unknown. The dystocia and fetal abnormalities cannot be definitively related to manipulation of the embryo or the uterine environment. Nevertheless, the cluster of clinical signs is suggestive of Large Offspring Syndrome, and presents multiple medically challenging perinatal complications. The calf's large birthweight, respiratory difficulties, and a secondary omphalitis required aggressive medical interventions including physical therapy, oxygen supplementation and monitoring, and umbilical resection. Anticipating these complications provided the necessary support for this otherwise vigorous calf to quickly overcome her setbacks and return to the farm.