Objective: To investigate the frequency, source, and risk factors of intraoperative (IO) surgeon and patient bacterial contamination during clean orthopedic surgeries, and to investigate the relationship between IO contamination and surgical site infection (SSI) in dogs. Study Design: Prospective clinical study. Sample Population: Client-owned dogs undergoing stifle surgery (n ¼ 100). Methods: IO cultures were taken in each case from surgical foot wrap, peri-incisional skin, surgical gloves, and the surgical team's hands. The environment (operating room [OR] lights, computers, scrub sink faucet, anesthesia gurney, and radiology table) was sampled every 5 months. Bacteria were identified and the contamination of each case was categorized. All gloves from the surgical team were collected and tested for perforations using a water infusion test. Cases were followed for at least 8 weeks to determine the presence or absence of SSI. Perioperative variables were evaluated for association with IO contamination and SSI. Results: Bacterial isolates were yielded from 81% of procedures from 1 or more sources; 58% had positive hand cultures, 46% had positive glove cultures, 23% had positive patient skin cultures, and 12% had positive foot wrap cultures. Staphylococcus spp. was the most commonly recovered bacteria. There was no apparent association between IO contamination and SSI. The highest level of environmental contamination was associated with the scrub sink faucet, followed by the radiology table, anesthesia gurney, and OR computers. The IO glove perforation rate was 18%. Conclusion: Clean orthopedic procedures commonly had clinically insignificant bacterial contamination. In our study, bacteria responsible for SSI did not appear to colonize the patient in the OR. In the veterinary literature, surgical site infection (SSI) rates for patients undergoing clean surgical procedures range from 3.6-5.8%. 1-3 Infection occurs despite adherence to well-accepted standards of surgical technique and environmental control designed to maintain a sterile surgical field. 4 Little objective information is available to validate how successfully these techniques control intraoperative contamination of surgical gloves, patient wraps, patient skin, and surgeon skin. In addition, it is not known how bacteria associated with surgical procedures influence complications. Understanding the bacterial ecology of veterinary operating rooms during the intraoperative period is critical in the search for the source of SSI, and allows for the development of evidence-based strategies to control the impact of pathogenic microbes in the surgical environment. In human surgical practice, published intraoperative glove contamination rates range from 14-56%. 5,6 Studies have not reported a clear primary source of contamination. One study reported surgical personnel, followed by the patient, and operating room environment as the most common sources of contamination 7 ; however, another study reported the operating room environment as the major source, followe...