Comparison of metrics to assess antibiotic use in small ruminants at a university referral clinic between 2005 and 2019.

Background: Monitoring antibiotic use is essential to provide a framework enabling veterinarians to use antibiotics prudently. Methods: Electronic medical records from the University of Veterinary Medicine's University Clinic for Ruminants in Vienna were analysed with respect to sheep and goat antibiotic doses administered over a 15-year period. Antibiotic use was assessed using total mg/kg, total milligrams, number of doses administered, Defined Daily Doses (nDDDvet) for cattle and estimated nDDD for sheep. Results: 5113 antibiotic doses were recorded over the 15-year period. Urinary tract disorders required the highest number of doses administered per animal (mean 16.9; median 16.0). Antibiotic use patterns varied according to the metrics used for analysis. By mg/kg, the largest proportion of antibiotics administered were penicillin/streptomycin (43.0% of the total mg/kg), followed by tetracyclines (17.3%) and sulfonamide/trimethoprim combinations (15.2%). By number of doses administered, the most frequently used antibiotics were penicillins (excluding combinations with streptomycin) (33.9% of total number of doses administered), fluoroquinolones (25.1%), 3rd/4th generation cephalosporins (13.6%) and penicillin/streptomycin (13.4%). Limitations: As the university clinic was a city-based referral centre, this analysis cannot be compared directly with antibiotic use in commercial herds or flocks. Conclusions: The considered choice of antibiotic use metrics is essential for an effective and meaningful analysis of the responsible use of antibiotics by veterinarians in practice.