Presence of Antimicrobials in Postrace Samples in Japanese Thoroughbred Racing

Ever since 'One Health' concept was introduced in early 2000s, judicious use of antimicrobials by veterinarians has become an issue of great concern. Recently, findings of anti-inflammatory effects in certain types of antimicrobials have raised a subject for discussion among racing authorities. Regulatory framework of antimicrobials in racing should be based on best interest of horse welfare and doping control perspective, but basic data on prevalence of antimicrobials are lacking. Analysis of 100 postrace urinary samples collected from 10 Japanese racecourses by targeting 21 antimicrobials using ultra performance liquid chromatography-tandem mass spectrometry resulted in detection of ceftiofur, cefalotin, cefalotin metabolite, dihydrostreptomycin, gentamicin, kanamycin, and oxytetracycline. Detection of antimicrobials critically important for resistance in human medicine was limited to a single sample. Oxytetracycline, which is known to possess anti-inflammatory effects, was detected in three samples. This may suggest the need for establishing a regulatory framework from doping control perspective and further studies to clarify pharmacologically relevant concentration of antimicrobials with such properties.