Abstract

Rocuronium is a neuromuscular blocker with potential to provide advantages in surgeries that require shortterm muscular relaxation. A sample consisting of 20 female canines submitted to ovaryhysterectomy was randomly divided into two equally sized groups. All the animals received acepromazine (0,1 mg.kg-1, IV), propofol (6,0 mg.kg-1, IV) and maintenance with isofluorane. Rocuronium (0,1 mg.kg-1, IV) was administered at the moment of the skin incision to the animals in the #x201C;rocuronium group#x201D; (GR). In the #x201C;control group#x201D; (GC), saline 0,9% was administered in equivalent volume of that used to rocuronium in double-blind study. Respiratory frequency (FR) and the minute-volume (VM) were measured before the beginning of the treatment (M0), 15 minutes after the administration of pre-anesthesic medication (M1), subsequent to induction (M2), and 2, 4, 6, 8, 10, 15, 20, 25, 30, 35 and 40 minutes after the administration of rocuronium or saline. The other variables were systolic blood pressure, heart rate and electrocardiography, measured at M0, M1, M2 and every 10 minutes from this last moment (M3, M4, M5 and M6). The collection of samples for blood gas analysis was performed at M0, M3 and M6. A questionnaire on the muscular relaxation was responded by the surgical staff right after the procedures. The results revealed that there were only a few alterations in the respiratory dynamics. A reduction on the VM was noted 2 minutes from the administration of rocuronium in the GR group when compared to the GC group. Both protocols produced acidemia, respiratory acidosis and hyperchloremia. No significant alteration was noted in the circulatory dynamics. The muscular relaxation was considered superior in 80% of the animals in the group treated with rocuronium when compared to the non-treated group.