Alcohol-based antisepsis without the use of chlorhexidine for arthroscopy in horses

Alcohol-based antisepsis has shown experimentally to be as effective as 4 % chlorhexidine gluconate (CHG) at reducing bacterial counts (colony forming units; CFU) on equine skin. Our objectives were to determine the immediate and post-surgical reduction in CFU/mL on equine skin prepared with CHG-based or 70 % isopropyl alcohol (IPA)-based (without CHG) protocols in a clinical setting with arthroscopic surgery. Our hypotheses were that the log₁₀CFU/mL reduction would not significantly differ between protocols immediately after preparation or at the end of surgery. Six horses underwent a 40 min bilateral tarsocrural joint arthroscopy with each limb randomly assigned to Group A or B. Group A tarsocrural joints underwent a rough scrub using 4 % CHG and a 5 min sterile scrub using 2 % CHG. Group B underwent a rough scrub with neutral soap followed by a 90 s sterile scrub with IPA. Samples were collected before rough scrub (T0), immediately after sterile scrub (T1), and end of surgery (T2). CFU/mL were determined in duplicate and were log-transformed and averaged. ANOVA models compared the immediate reduction (T0-T1) and sustained reduction (T0-T2) between treatment groups. The immediate and sustained log10CFU/mL reduction between groups was not different (P = 0.46, P = 0.42). Both groups achieved at least a 2-log immediate and sustained reduction. Limitations include small population size, short surgical duration, length of follow-up, and researchers were not blinded to treatment during sampling. This study demonstrates efficacy of IPA-based antisepsis, without the need for CHG, and supports further investigation in clinical surgery as an acceptable method of surgical site preparation.