OBJECTIVE: To (1) determine suction tip (intermittent and continuous mode) contamination rate in orthopedic surgery in dogs and cats; (2) examine the effect of surgical time on contamination; and (3) report bacteria isolated. STUDY DESIGN: Clinical study. SAMPLE POPULATION: Clean orthopedic surgeries (n = 50). METHODS: Surgical procedures were assigned to 1 of 2 groups: (1) continuous (n = 25) or (2) intermittent suction (n = 25). A control suction was operated in each surgery. Samples for aerobic and anaerobic bacteriologic examination were collected from the surgical suction at 0, 20, 60 minutes, and at the end of surgery, and from the control suction at the end of the surgery only. Comparison of continuous and intermittent suction data, and the effect of surgical time on contamination rate were analyzed using a Kaplan-Meier survival analysis followed by a Cox proportional hazards model. P < .05 was considered significant. RESULTS: Aerobic contamination occurred in 22 of 50 surgical procedures and there was no anaerobic growth. There was no significant difference between continuous and intermittent suction mode groups (P = .40). Surgical time did not influence the contamination rate (P = .79). Bacterial cultures mainly revealed coagulase-negative Staphylococci, however multiresistant bacteria were isolated. CONCLUSIONS: We failed to find superiority of the intermittent operation mode of the suction tip over the continuous mode. A safe time frame before contamination of the suction tip occurs that could not be defined.