Anoxia in the bovine foetus

Laparohysterotomies were performed, under local analgesia, on 18 plurigravid Herefore cattle and the response of their foetuses to anoxia was examined. All control and 4 of 6 foetuses subjected to 4 minutes of anoxia survived whereas all others died when the umbilical cord was clamped for 6 or 8 minutes. Death mostly occurred just before or soon after delivery, which was undertaken immediately following release of the umbilical clamp. In 2 cases, however, the calves survived for at least 2 days before being slaughtered when death appeared imminent. During the intervening period both animals failed to suck although one was able to stand temporarily following the oral administration of glucose and milk. Studies on the blood-gas and acid-base status of the foetuses while the umbilical cord was clamped revealed a decline in pH, pO2 and standard bicarbonate levels, the development of a base deficit and an increase in pCO2 and lactate levels. Clamping of the umbilical cord usually resulted in some foetal movement and the release of meconium. Clamping of the imbilical cord also caused an almost immediate fall in the pulse rate, which gradually increased after several minutes and became irregular and weak. Post-mortem examination of foetuses or calves dying from anoxia revealed haemorrhages throughout the body, these always being found on the heart, usually in the thymus and spleen, and occasionally in other sites throughout the body.