Gastrointestinal colic in mares during early pregnancy may require general anesthesia for surgical correction. There is a scarcity of literature identifying anesthetic risk factors associated with negative outcome in the pregnant mare. In this case report, a seven-year-old Thoroughbred broodmare, presenting for the investigation and treatment of colic in the fifth month of pregnancy, underwent surgery for the correction of right dorsal displacement of the large colon. Intraoperatively, interventions for maternal hypoxemia and hypotension were necessary. The mare recovered well from general anesthesia and was discharged from the hospital eleven days postoperatively. In this case report, the successful anesthetic management of a pregnant broodmare is described, and all aspects that may improve the outcome for both mare and fetus are considered, with emphasis on the prevention of cardiovascular and respiratory disturbances.