Standing Enucleation in the Horse: A Report of 5 Cases
Enucleation was performed in 5 horses under local anesthesia and sedation with the horse standing. Minimal hemorrhage occurred during the surgical procedure, and there were no other reported complications. Standing enucleation is a surgery that is safe to perform in horses.
Enucleation, transpalpebral or subconjunctival, is the surgical removal of the globe, conjunctiva, and nictating membrane. For transpalpebral enucleation, the eyelids are closed to prevent orbital contamination. It is performed when severe ocular injury is present, such as severe corneal infection, endophthalmitis, corneal or adnexal neoplasia, or severe corneal lacerations (1–5). Enucleation is also performed in cases of severe ocular trauma or in horses with a painful, blind eye (2). In subconjunctival enucleation, the globe is removed prior to removal of the eyelid margin, allowing for decreased surgical time and hemorrhage, but increased contamination from the globe than with the transpalpebral technique (1–5).
Although enucleation in the horse has been described as a surgery to be performed under general anesthesia, (7), surgery under sedation and with local anesthesia to remove corneal foreign bodies, perform nictitans surgery, repair eyelids, or excise tumors has been done with the horse standing (6).
A retrospective study was performed to document cases of standing transpalpebral enucleation in the horse. Our hypothesis was that enucleation could be performed safely in the standing, sedated horse.
Materials and methods
The medical records of all horses requiring an enucleation at the Marion DuPont Scott Equine Medical Center (MDSEMC) between March 1, 2005, and March 1, 2006, were reviewed to determine whether the procedure had been performed under standing sedation or general anesthesia. Horses that received standing sedation for the enucleation were included and for them, the age, sex, breed, history, previous treatment of the eye, clinical findings, medical treatment, and outcome of the enucleation were recorded.
All horses had been sedated with a single administration of xylazine hydrochloride (Anased; BenVenue Laboratories, Bedford, Ohio, USA), 0.3–0.4 mg/kg bodyweight (BW), IV, and detomidine hydrochloride (Dormosedan, Pfizer, New York, New York, USA), 0.01 mg/kg BW, IV, and then placed in standing stocks. Additional doses of xylazine hydrochloride, 0.2–0.3 mg/kg BW, and detomidine hydrochloride, 0.01 mg/kg BW, were administered, IV, as needed to keep the patient sedated throughout the procedure. The horses received 1 dose of flunixin meglumine (Vetagesic; Vedco, St. Joseph, Missouri, USA), 1.1 mg/kg BW, IV, preoperatively. One horse received 1 dose of gentamicin sulfate (GentaVet100; Vedco), 6.6 mg/kg, IV, prior to surgery.