DYSTOCIA Patrick M. McCue DVM, PhD, Diplomate American ...

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DYSTOCIA Patrick M. McCue DVM, PhD, Diplomate American ...

DYSTOCIAPatrick M. McCueDVM, PhD, Diplomate American College of TheriogenologistsDystocia. The word alone is enough to sendshivers down the spine of horse breeders andkeep them awake at night. The termdystocia refers to an abnormal or difficultbirth. Dystocia occurs in approximately 1 to2% of foalings and are more common inmares during their first foaling than in maresthat have had multiple foals. The mostcommon cause of dystocia in the mare is anabnormal alignment of the head or forelimbsof the foal in the birth canal.Foaling is usually a rapid and forceful event.As a general rule, once a mare has brokenher water and is in active labor, the front feetand a nose should be visible at the vulvawithin 10 minutes. Complete delivery of thefetus is normally accomplished within 20 to30 minutes after the mare breaks her water.If no progress has been made by 15 minutes,a vaginal examination should be performedby an experienced individual to assessposition of the fetus. A veterinarian shouldbe consulted if no progress has been madeby 20 minutes after the water has broken, iflabor has stopped completely or if thenormal progression of foaling has beeninterrupted. A delay in labor may result incompromise to the health of the fetus whenoxygen delivery is decreased as the placentabegins to separate from the uterus of themare.The goals in managing a mare with adystocia are to save the life of the foal, savethe life of the mare and to preserve thefuture fertility of the mare. It is importantthat a brief physical examination beperformed to identify the obstetricalproblem, determine if the fetus is alive andto formulate a plan. Caution should be usedif a mare experiencing a dystocia is to beexamined in stocks, because many foalingmares try to lie down during vaginalexamination. Veterinary intervention mayinclude sedation of the mare, an epiduralanesthetic to decrease pain and strainingand/or general anesthesia to facilitate safeevaluation of the mare and correction of theproblem.Choices for relieving an equine dystociainclude vaginal delivery, cesarean sectionsurgery or fetotomy. The final decision maydepend on the status of the fetus, durationand severity of the dystocia, economic valueof the mare and fetus, clinician expertise,client preference, facilities available andother considerations. If a fetus is alive, avaginal delivery may be attempted with themare awake. If significant progress is notmade in 15 to 20 minutes, the mare may beput under general anesthesia and an assistedvaginal delivery attempted. If progresstoward a vaginal delivery is notforthcoming, a cesarean surgery is oftenperformed.1


Elevation of the hindquarters of ananesthetized mare may be beneficial toincrease space in the caudal abdominalcavity and therefore make it easier toreposition fetal body parts that are notaligned properly in the birth canal. Liberalapplication of obstetrical lubricants along allsides of the fetus and within the uterinecavity will greatly enhance repositioningand extraction of the fetus.It is critical that careful traction be appliedto the fetus once it has been confirmed thatthe limbs and head are correctly alignedwithin the birth canal. It is recommendedthat the amount of traction used to pull anequine fetus not exceed that provided by twopeople. In addition, mechanical devicesshould never be used to pull an equine fetus.Traction should only be applied when themare is pushing and traction should bereleased when the mare stops straining.Special immediate attention must be givento the foal following a dystocia. The foal isat high risk of many neonatal diseasesincluding, neonatal maladjustmentsyndrome, failure of passive transfer,ruptured bladder and trauma, such as ribfractures. The mare should also beexamined in due course following resolutionof a dystocia. It is common for the placentato be retained following a dystocia andpreventative treatments are often institutedafter a dystocia has been relieved. Finally,the reproductive tract of the mare (i.e.perineum, vagina, cervix and uterus) shouldbe carefully examined for trauma that maylimit her future reproductive performance.Resuscitation equipment should be availableon farms that foal out a lot of mares andfarm personnel should be trained in theproper care and use of the equipment. The‘Foal Resuscitator’ (www.mccullochmedical.com) is a simple-to-use device that can besafely applied to foals by farm personnel tohelp stimulate breathing in a newborn foal.2

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