Antimicrobial drug use in horses undergoing colic surgery in Germany A questionnaire-based survey of 68 German equine hospitals was performed in order to acquire data of postoperative short-term incisional complications and of antimicrobial use in horses undergoing celiotomy. The questions asked included the following: type of antimicrobial drug used, method of drug dosage determination, timing of application and duration of antimicrobial treatment, number of performed colic surgeries per year, time to discharge from the hospital after laparotomy, incisional complication rate (occurring before discharge from clinic), most commonly cultured bacteria and specification and frequency of multi-resistant bacteria. The questionnaire was completed by 33.8 % of the contacted equine hospitals. The combination of penicillin and gentamicin was the most frequent (34.8 %) used antimicrobial therapy. 47.8 % of the responding equine hospitals are using local antimicrobial therapy (mainly intra-abdominal just before wound closure). The majority does neither weight the horse nor uses a weight tape to determine body weight. Mean duration of antimicrobial use was five days. The average number of celiotomies per clinic and year was 74. Mean time to discharge was nine days after surgery. Overall, incisional complications were stated to occur rarely. Staphylococcus spp. and Enterobacteriacae spp. were the most commonly isolated bacterial populations. The detection of multi-resistant bacteria was stated to be "rare" or "never detected". Results of this study offer an inconsistent regime of perioperative antimicrobial prophylaxis in equine hospitals in Germany. Introduction of guidelines for antimicrobial use might lead to more prudent use of antimicrobials and might help to reduce the development of resistant bacteria as well as incisional infections.