The Pregnant Mare and Perinatology: 10th International Symposium on Equine Reproduction Recap

The 10th International Symposium on Equine Reproduction July 26-30 at the University of Kentucky was presented in four sessions: the non-pregnant mare, the stallion, conception and early development, and the pregnant mare and perinatology. Irwin K. Liu, PhD, Department of Population Health and Reproduction, School of Veterinary Medicine at the University of California, Davis, recaps the pregnant mare and perinatology session:

  • Investigations on manual reduction of twin pregnancies suggests that location of twins does not significantly affect foal mortality, but age of the mare (greater than nine years old) yields lower live foal rates. Veterinary experience did not play a role in live foal rates, as all individuals had performed more than 20 reductions previously.
  • A few studies focused on placentitis (inflammation of the placenta) in the pregnant mare. The investigations revealed that measurement of the combined thickness of the uterus and placenta alone was not a good indicator of pending abortion. One report examined several pregnant mares that exceeded the normal upper limits of uterine-placental thickness (combined thickness of the uterus and placenta) yet delivered live and normal foals without evidence of placentitis. Thus, other signs of pending abortion, such as placental separation, vaginal discharge, and amniotic fluid opacity are essential in the diagnosis of impending abortion in the mare. Other studies also indicated that early intervention of placentitis with antibiotics was essential for a successful outcome and that antibiotics were most important when compared with other treatments, such as progesterone, non-steroidal anti-inflammatory agents (NSAIDs), or aspirin. Another study indicated that mares that have successfully foaled following the diagnosis and treatment of placentitis should be treated post-foaling, as bacteria continues to be present in the uterus.
  • There were many studies of early or late pregnancies that attempted to define what physiological or chemical factors and signals are associated with the development of the fetus, its interaction with the uterus, and what keeps this marriage viable. While this area of investigation is of little practical significance, it is important to understand what is normal before determining what is abnormal and thus, developing treatment strategies to maintain pregnancies in the mare.
  • A relatively new modality to veterinary medicine is three-dimensional ultrasonography. This modality was presented by a group from Japan that clearly demonstrated its value, potential usefulness, its accuracy in the analyses of fetal normality and abnormality, and gender determination during early and late stages of pregnancy in the mare.
  • Investigations on uterine blood flow in the pregnant mare while under a short-term (70-day) treatment of pentoxiphylline (an agent that increases blood flow) did not increase blood flow in aged pregnant mares with endometrosis (chronic degenerative endometritis, an inflammation of the lining of the uterine wall after breeding).
  • A high abortion rate in mares in one region of Australia indicated the abortions were similar to those caused by Mare Reproductive Loss Syndrome (MRLS) in Kentucky and were attributable to a certain species of caterpillars. Another presentation suggested the Australian abortions, MRLS in Kentucky, and Nocardia placentitis are similarly linked and are likely a variation of one another.

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