Evans LK, Knowles TG, Werrett G, Holt PE. Division of Companion Animals, Department of Clinical Veterinary Science, University of Bristol, Bristol. JAAHA 2009 Sep-Oct 50 9 458-65 OBJECTIVES: To determine the use in practice and efficacy of different concentrations of chlorhexidine gluconate for canine pre-operative skin preparation. METHODS: Questionnaires were used to establish which antiseptics and techniques were used for patients undergoing elective neutering. In a clinical study, five different concentrations of chlorhexidine gluconate - 0 per cent (tap water, as a control) 1, 2, 3 and 4 per cent - were tested on 50 dogs undergoing elective ovariohysterectomies and orchidectomies. RESULTS: A variety of preparation practices occurred but only 21 per cent of the veterinary nurses surveyed were aware of the concentration and contact time they used whilst preparing animals. The clinical study revealed there was a significant difference (P<0.001) between the different concentrations used. All concentrations of chlorhexidine were significantly more effective than the control tap water. There was a tendency towards increasing efficacy as concentration increased from 1 to 4 per cent but this was not statistically significant. CLINICAL SIGNIFICANCE: The lack of significant differences in efficacy between the different concentrations of chlorhexidine gluconate means that current practices may be adequate, although if the chlorhexidine gluconate concentrations and contact times used are unknown, they may be lower than those tested here and, possibly, ineffective, especially if contact times are short.