A review of the causes of abortion in UK mares and means of diagnosis used in an equine studfarm practice in Newmarket

A retrospective survey of the records of 210 postmortem examinations of aborted equine foeti and placentae, performed at the authors’ practice laboratory, revealed that umbilical cord vascular compromise was the most common diagnosis made, accounting for almost 50% of cases. Abortions associated with twin pregnancy now account for a relatively small percentage (2.9%) of cases as compared to much higher incidences (22–29%) seen prior to the introduction of ultrasound scanning and multiple pregnancy reduction techniques in routine equine studfarm practice. Placental abnormalities accounted for 53 (25.2%) of the diagnoses. 14 (6.7%) were caused by Equid Herpesvirus-1 infections. The cause of the abortion was not established in 11 (5.2%) of the cases.