Ropivacaína isolada ou associada à morfina, butorfanol ou tramadol pela via peridural em cadelas para realização de ovariosalpingohisterectomia

The aim of this study was to investigate the use of ropivacaine combined or not with different opioids, for epidural anesthesia in bitches submitted to elective ovariosalpingohisterectomy (OSH). Thirty two mixed-breed female dogs, adults were used with medium weigh of 10.5kg. The animals were premedicated with acepromazine (0.05mg.kg-1, IM) and midazolam (0.2mg.kg-1, IM) and allocated in four experimental groups: group 1(n=8): ropivacaine: 0.3 mL.kg-1; group 2(n=8): ropivacaine + morphine (0.1 mg.kg-1); group 3(n=8): ropivacaine + butorphanol (0.1 mg.kg-1); and group 4(n=8): ropivacaine + tramadol (0.5 mg.kg-1) administered epidurally. Heart and respiratory rate; systolic arterial pressure; rectal temperature; arterial blood gas partial pressures; blood pH; sedation and muscular relaxation degree were evaluated at different experimental moments. The data were submitted to ANOVA and compared by Kruskal Wallis, Friedman, Dunn, Tukey and Chi-square test (p≤0.05). Minimum cardiorespiratory alterations were observed and the group of the ropivacaine combined with the butorphanol (G3) presented a more cranial blockage, what allowed the accomplishment of OSH without induction in six animals (75%) whereas most of the others needed anesthetic rescue. The results allow us to conclude that the use of ropivacaine sole or combinated with morphine, butorphanol or tramadol, for epidural anesthesia, didn't promote significant cardiorrespiratory depression and the ropivacaine associated to the butorphanol allowed the accomplishment of OSH in bitches.