Prostaglandin facilitated mare foal bonding in a pregnant nurse mare

Abstract

Nurse mares provide an invaluable service for orphaned foals; however, there is often negative public perception surrounding the nurse mare industry. Although pharmacologically induced lactation can reduce the number of nurse mare foals, some nurse mare owners stipulate that a nurse mare must be rebred and returned in foal. Catastrophic injury and illness affecting the broodmare after foaling is often unpredictable and may occur anytime during a foal’s first few months of life. Unpredictability and length of physiologic breeding season may contribute to an excessive number of foals that need nurse mares. Although the need for nurse mares may not be eliminated, the following case report demonstrates that the number of nurse mares could be reduced. A 9 year old multiparous Paint mare was presented as a nurse mare for a 48 day old orphan foal whose dam was euthanized on humane grounds. Mare foal bonding was achieved following prostaglandin administration. While on farm, this nurse mare was bred via live cover and became pregnant. A 40 day old foal was orphaned when its dam was euthanized during colic surgery. Due to lack of nurse mare availability, the original orphan foal was weaned at 147 days in an attempt to graft the new orphan to this mare. Prior to the second mare foal bonding session, transrectal ultrasonography was performed to confirm fetal viability. Plasma progesterone concentrations were 8.42 ng/ml. The mare was administered altrenogest (Regumate,® 0.044 mg/kg, PO) followed by a dose of prostaglandin (Lutalyse,® 10 mg, IM) to facilitate mare foal bonding. Nurse mare bonding was successful and this mare remained on altrenogest for 30 days. Transrectal ultrasonography and blood sampling were repeated on days 5 and 22 following prostaglandin treatment and circulating progesterone concentrations were 0.79 and 5.18 ng/ml, respectively. With appropriate progestin supplementation, prostaglandins may still be utilized in mare foal bonding in a pregnant nurse mare, despite luteolytic effects.