Causes of abortion, stillbirth, and perinatal death in horses: 3,527 cases (1986–1991)

TLDR

The study reviewed pathology records of 3,514 aborted or stillborn foals and 13 placentas from mares with weak foals to identify causes of abortion, death, or illness. Fetoplacental infections (bacterial, viral, fungal, or undefined placentitis) were the most frequent cause of abortion or neonatal death, followed by birth complications in 19 % of cases; other common causes included placental edema or separation, twin development, contracted foal syndrome, congenital anomalies, and umbilical cord abnormalities, while leptospirosis and nocardioform actinomycete infections were notable bacterial contributors.

Abstract

Pathology case records of 3,514 aborted fetuses, stillborn foals, or foals that died < 24 hours after birth and of 13 placentas from mares whose foals were weak or unthrifty at birth were reviewed to determine the cause of abortion, death, or illness. Fetoplacental infection caused by bacteria (n = 628), equine herpesvirus (143), fungi (61), or placentitis (351), in which an etiologic agent could not be defined, was the most common diagnosis. Complications of birth, including neonatal asphyxia, dystocia, or trauma, were the second most common cause of mortality and were diagnosed in 19% of the cases (679). Other common diagnoses were placental edema or premature separation of placenta (249), development of twins (221), contracted foal syndrome (188), other congenital anomalies (160), and umbilical cord abnormalities (121). Less common conditions were placental villous atrophy or body pregnancy (81), fetal diarrhea syndrome (34), and neoplasms or miscellaneous conditions (26). A diagnosis was not established in 16% of the cases seen (585). The study revealed that leptospirosis (78) was an important cause of bacterial abortion in mares, and that infection by a nocardioform actinomycete (45) was an important cause of chronic placentitis.