The use of clenbuterol in large animal obstetrics: manual correction of bovine dystocias.

This study was undertaken to test the effect of clenbuterol, a smooth muscle relaxant, as an aid for the manual correction of bovine dystocias in a rural Quebec practice. The drug was given initially by intravenous coccygeal or jugular injection at a dose of 0.6 micrograms-0.8 micrograms/kg of body weight to parturient cows affected with fetal malpresentations (n = 37), malpostures (n = 112), or uterine torsions (n = 70). These cases comprised 32% (219/688) of the manually corrected dystocias encountered in cattle during the trial. Ease provided for obstetrical maneuvers of different types of dystocias was the evaluation criteria used in this report. The drug's myometrial relaxant effect made corrections easier for the veterinarian, and shorter and less traumatic for the dam. The success rates achieved for vaginal corrections and delivery of uterine torsions were 84% (76/91) and 77% (70/91), respectively. Other recorded benefits included the need for less frequent use of epidural anesthesia and a significantly lower incidence of retained fetal membranes (chi 2 = 11.18, p < 0.001). No adverse reactions were observed at any time. Clenbuterol proved to be a useful drug for manual correction of dystocias in cattle.