Winter, D. C.; Monzem, S.; Spiller, P. R.; Stocco, M. B.; Gomes, L. G.; Travagin, D. P.; Venêga da Conceição, E. D.; Guimarães, L. D. Effects of Epidural Anesthesia With Tramadol, Ropivacaine or Tramadol-Ropivacaine Combination, in Bitches Undergoing Ovariohysterectomy under Anesthesia With Isoflurane. Semina: Ciênc. Agrár. 2016, 37, 4063-4076.