Dystocia
Normal parturition with no complications is by far the most common occurrence in domestic animals. Dystocia is difficult birth; in some cases, birthing is not possible without assistance.
in general, from the onset of labor, cows should calve within 8 hours, ewes should lamb within 2 hours, and mares should foal within 2 to 3 hours. sows should average one offspring per hour until farrowing (i.e., birthing of a litter) is complete.in large animals (cow, mare, and ewe), improper fetal presentation is a common cause of dystocia, and typically with abnormal positioning of the limbs or head (e.g., head rotated up and ventrum of neck presented or head rotated down and dorsum of neck presented). Correction of such a presentation may be necessary for delivery of the fetus. Correction usually entails repelling the fetus into the uterus away from the pelvic inlet so that the fetus can be manipulated and the position of its limbs and head changed.
Excessive size of the fetus relative to the size of the birth canal of the dam may also produce dystocia. This is a common cause of dystocia in first-calf heifers and in relatively small cows mated with much larger bulls. Excessive fetal size may also produce problems in ewes with single lambs and sows with small litters. Even though the presentation may be normal in these cases, excessive traction may be required to deliver the newborn, and this may damage both the fetus and the dam.
A cesarean section (surgical removal of the fetus) may be necessary in some cases of dystocia. successful surgeries produce a viable fetus and preserve the reproductive capacity of the dam. An embryotomy (surgical dismemberment of the fetus to permit its passage through the birth canal) may be necessary in some cases to save the life of the dam.