ABSTRACT. Otero A.R. dos S., Barbosa V.F., Carneiro R.L., Martins Filho E.F., de Azevedo M.C., Santos B.C.P., Gordilho Filho A. de O. & da Costa Neto J.M. [Evaluation of continuous infusion of dexmedetomidine or dexmedetomidine-midazolam on cardiorespiratory variables and quality of anesthetic recovery, in bitches submitted to ovariosalpingohysterectomy.] Avaliação da infusão contínua de dexmedetomidina ou dexmedetomidina-midazolam sobre variáveis cardiorrespiratórias e qualidade da recuperação anestésica, em cadelas submetidas à ovariosalpingohisterectomia. Revista Brasileira de Medicina Veterinária, 38(2):168-174, 2016. Departamento de Anatomia, Patologia e Clínicas Veterinárias, Escola de Medicina Veterinária e Zootecnia, Universidade Federal da Bahia, Av. Adhemar de Barros 500, Salvador, BA 40170-110. Brasil. E-mail: firstname.lastname@example.org The aim of this study was to evaluate the cardiorespiratory effects and quality of anesthetic recovery due to the continuous infusion of dexmedetomidine associated or not with midazolam in bitches submitted to ovariosalpingohisterectomy. Twenty healthy adult bitches were distributed on two groups named dexmedetomidine group (GD) and dexmedetomidine-midazolam group (GDM). All animals received atropine (0.044 mg/kg) and, after 15 minutes, propofol IV was infused in a dose sufficient to orotracheal intubation and anesthesia was maintained with isofluorane. GD group received bolus administration of dexmedetomidine (2 μg/kg) followed by continuous infusion (2 μg/ kg/h). GDM group received the same treatment plus midazolam in a dose of 0.2 mg/kg and 0.2 mg/kg/h respectively. The bitches were submitted to ovariosalpingohisterectomy and cardiorespiratory data were registered immediately before dexmedetomidine or dexmedetomidine and midazolam administration (M0) and sequentially, every ten minutes, for 40 minutes (M1 to M4). Times and quality of anesthetic recovery were evaluated. There were an initial increase of arterial pressures (SAP, DAP, MAP) and decrease of heart rate (HR) in GD group. The association dexmedetomidine-midazolam resulted on improved hemodynamic stability. Both protocols are considered secure and provide adequate anesthetic recovery.