Preemptive methadone or tramadol for control of postoperative pain in canine ovariohysterectomy and mastectomy - Ramirez Uscategui, R. [UNESP]; Faria Tiosso, C. de [UNESP]; Vitti Moro, J. [UNESP]; Rossi Feliciano, M. [UNESP]; Nassar Coutinho, L. [UNESP]; Russiano Vicente, W. [UNESP] (Wiley-Blackwell, 2013)