The objective of the present study was to compare between three anesthetic protocols for long-term anesthesia (2 h); protocol 1: xylazine (1mg/kg)/ketamine (10mg/kg) and inhalation of isoflurane in 100% of oxygenprotocol 2: xylazine (1mg/kg)/ketamine (10mg/kg) and propofol (24mg/kg/h) by CRI, and protocol 3: propofol (5mg/kg) and propofol (12mg/kg/h) by CRI. Three clinically healthy adult mongrel dogs of both sexes were used. Food and water were withheld for 12 and 6 h before induction of anesthesia, respectively. Intravenous catheter was placed in the cephalic vein. A wash-out period of 15 days was allowed between protocols. For all protocols (1, 2, and 3), physiological parameters were recorded using a patient monitor. Depth of anesthesia and muscle relaxation were determined by recording various reflexes. Times of first limb movement, regaining swallowing reflex and extubation, sternal recumbency, and standing were recorded. Quality of recovery was also recorded. Venous blood samples were collected into EDTA-containing Vacutainer tubes immediately before anesthesia, 10min after induction with ketamine/propofol, one hour and two h of anesthesia and after complete recovery for hematological analysis by using an automated machine. Data were recorded and expressed as mean±SD and analyzed with commercial statistical software. Results revealed slight variations among animals of the three protocols in the physiological parameters. The quality and depth of anesthesia were excellent in dogs anesthetized with isoflurane and were good in dogs during propofol infusion. The duration of deep anesthesia during propofol …