Established immobilization protocols are required for safe procedures on wildlife and zoo animals. This study evaluated the cardiovascular, respiratory, and anesthetic effects of dexmedetomidine (40 μg/kg) with S-ketamine (5 mg/kg) and midazolam (0.5 mg/kg) with S-ketamine (5 mg/kg) in 12 specimens of oncilla (Leopardus tigrinus) at Quinzinho de Barros Municipal Zoo Park in Sorocaba, São Paulo, Brazil, between January and March 2010. Each animal underwent both protocols, totaling 24 anesthetic procedures. The dexmedetomidine–S-ketamine group (DK) showed a decrease in heart rate compared to initial values and significantly lower heart rate and oxyhemoglobin saturation values compared to Midazolam–S-Ketamine Group (MK). Four animals in DK had episodes of sinus pauses. Systemic blood pressure, respiratory frequency, and rectal temperature showed no significant differences between groups. The dexmedetomidine–S-ketamine group showed a greater degree of muscle relaxation and allowed for more thorough and longer oral evaluations. The dexmedetomidine–S-ketamine group had a shorter period of recumbency, longer period to return of muscle tone, and shorter recovery time. Two animals in MK did not reach recumbency. The dexmedetomidine–S-ketamine group had better qualities of induction and recovery. It may be concluded that both protocols can be safely used in oncillas. Midazolam–S-ketamine promotes effective chemical restraint for quick and minimally invasive procedures and dexmedetomidine–S-ketamine promotes effective chemical restraint for prolonged and more invasive procedures.