Dystocia in the horse is defined as stage 2 labor exceeding 30 min.1 A 20-year-old Przewalski’s horse mare was discovered in stage 2 labor. Fetal membranes protruded through the vulva, and over the ensuing 2 h, the mare remained quiet, but labor did not progress. Immobilization was necessary for reproductive examination, and the mare was anesthetized with detomidine (Pfizer Animal Health, Exton, PA, USA; 0.26 mg/kg IM) and carfentanil (Wildlife Pharmaceuticals, Fort Collins, CO, USA; 21 µg/kg IM).
Vaginal examination revealed an open cervix with the fetus in anterior presentation, dorsopubic position, and ventroflexion of the head and flexure of all limbs. Despite repeated attempts, the fetus could not be delivered. No signs of life were encountered in the foal. Cesarean section was elected over fetotomy. A right paralumbar surgical approach was made, and a routine hysterectomy was performed. A dead but grossly normal, fully developed fetus and normal placenta were extracted. Oxytocin (Bimeda-MTC Animal Health, Cambridge, Canada; 0.06 U/kg IV) and anesthetic antagonists were administered postoperatively. Postmortem exam concluded this was a uterine body pregnancy. There has been at least one other live foal resulting from a uterine body pregnancy in this collection, though not from this mare.
The mare remained hospitalized for 6 weeks. Perphenazine (Kryon Laboratories, Benrose, South Africa; 0.5 mg/kg IM) was used to keep the animal calm. Moderate incision swelling and ventral edema were the only significant postoperative complications. This is the first report of dystocia and Cesarean section in a Przewalski’s horse.
The authors thank the Department of Mammalogy and the Wildlife Health Center staff, who generously invested their time and shared their expertise in caring for this special animal and helping to achieve a successful outcome.
1. Norton JL, et al. Retrospective study of dystocia in mares at a referral hospital. Equine Vet J. 2007;39:37–41.