A field laparotomy technique for observing the reproductive tract of free-ranging desert bighorn sheep (Ovis canadensis cremnobates)

A surgical procedure was developed to observe the reproductive tract of free-ranging desert bighorn sheep (Ovis canadensis cremnobates) ewes. Ventral laparotomies were performed on 37 bighorn ewes (ages: lamb — 9 years of age), 24 of which were unilaterally ovariectomized. A second laparotomy was done on 31 ewes. Diazepam (1.5 mg/kg) was injected intramuscularly as a preanesthetic followed by 5 mg etorphine hydrochloride (M99) for restraint and anesthesia. Atropine sulfate (0.03 mg/kg) was used to control hypersalivation and bronchial mucus secretion. Diazepam was evaluated as a preanesthetic on a control group of 42 ewes not submitted to surgery. Pretreatment with diazepam significantly (P < 0.001) reduced the induction time of the anesthetic. All bighorn sheep subjected to surgery recovered without postoperative complications. Ambulation time was similar whether or not diazepam was used as a preanesthetic. Subsequent reproductive performance and mortality rates were similar to those bighorn sheep in the remaining population.