Prolonged anesthesia using sevoflurane, remifentanil and dexmedetomidine in a horse.

History: A 10-year old Arabian mare had a slow-growing mass on the lower right mandible and required a large partial mandibulectomy.

Physical Examination: No abnormalities were detected apart from the mass.

Management: A temporary tracheostomy was performed pre-operatively. Anesthesia was induced with xylazine followed by ketamine and diazepam. For 13 hours, anesthesia was maintained using sevoflurane, dexmedetomidine and remifentanil infusions, with the exception of surgical preparation time. Intra-operatively, ventilation was delivered through the cuffed tracheotomy tube. Heart and respiratory rates, ECG, arterial pressures, inspired and expired gases, pulse oximetry values and body temperature were monitored. Dobutamine and whole blood were necessary, and romifidine was used to control recovery. Post-operatively, phenylbutazone and buprenorphine given systemically and bupivacaine administered through a wound soaker catheter were used to provide analgesia. Head-shaking from buprenorphine was controlled with acepromazine and detomidine once standing after 87 minutes in recovery. For 3 days after surgery, analgesia was provided with butorphanol, phenylbutazone and bupivacaine. The mare recovered well, appeared comfortable and started eating the following day with no signs of ileus.

Follow-up: Seven months later, the mare was doing well.

Conclusions: Sevoflurane, dexmedetomidine and remifentanil infusions were suitable for a long and invasive procedure.