Conventionally performed equine ovariohysterectomy (OHE) is a technically demanding surgery associated with a high degree of invasiveness and morbidity. Hand-assisted laparoscopic surgical technique allows introduction of a hand through a portal into the laparoscopic field to facilitate surgical manipulation while maintaining abdominal insufflation and laparoscopic visualization. The purpose of this study was to develop and evaluate a hand-assisted laparoscopic OHE technique for dorsally recumbent horses. The surgical technique was developed in terminal (2 mares) and subsequently evaluated in 6 survival procedures. Mares were fasted 48 hours, anesthetized and positioned in dorsal recumbency for laparoscopic surgery. A hand access device (Omniport) was placed in a caudal midline laparotomy followed by 4 laparoscopic portals. Transection of the ovarian pedicle and broad ligament was achieved using a combination of a laparoscopic stapling instrument, an ultrasonically activated instrument and endoscopic clips. The genital tract was exteriorized through the laparotomy, and the body of the uterus transected and sutured in conventional pattern. Horses were evaluated through postoperative day 14 when a post mortem evaluation was performed. Four mares recuperated well after surgery, 1 mare was euthanized due to bilateral femur fractures sustained during anesthetic recovery and another developed severe pleuropneumonia. At necropsy all but one abdominal incision was healing routinely. One mare had abscessed along the laparotomy incision and developed visceral adhesions. Uncomplicated healing of transected mesovarial, mesometrial and uterine remnants was observed in all recovered mares. Hand-assisted laparoscopic OHE technique represents a minimally invasive and technically feasible alternative for conventional OHE. Careful patient selection and preparation may reduce the complications observed in this study. / Master of Science