Foaling rates and risk factors for abortion in pregnant mares presented for medical or surgical treatment of colic: 153 cases (1993-2005).

The purpose of this study was to determine foaling rates in mares presented for medical or surgical treatment of colic, and to examine risk factors associated with abortion following colic. A retrospective analysis of 153 medical records found that mares treated surgically for colic (P = 0.0007) were 3.5 times more likely to have a negative pregnancy outcome than were mares treated medically for colic. Anesthetic time (P = 0.01) and intra-operative hypotension (P = 0.03) were significantly associated with negative pregnancy outcome. Mares with an anesthetic time > or = 3 h were 6 times more likely to abort. Signs of endotoxemia (P = 0.30), hypoxia (P = 0.89), flunixin meglumine administration (P = 0.13), mucous membrane color at the time of presentation (P = 0.82) and capillary refill time (P = 0.76) were not associated with pregnancy outcome. There was no difference in the foaling rate for mares that had received progestin supplementation versus those that had not (P = 0.42). In this study, the significant risk factors for abortion were surgically treated colic, long anesthetic time, and intraoperative hypotension.