Enrofloxacin in dairy cattle with Escherichia coli mastitis.

per cent compared with 57.1 per cent, respectively). Bacteriological cure rates were significantly higher in the enrofloxacin group on day 2 (odds ratio for cure was 3.32, P=0.002). Bacteriological cure rates on day 21 were similar in both treatment groups (90.5 per cent in the enrofloxacin group and 86.8 per cent in the non-treated group). Survival rates of cows at day 21 or survival in the herd at six months did not differ between the two treatment groups. Quarter milk production returned in 21.8 per cent of cows in the enrofloxacin group and 37.3 per cent of the untreated cows. Study weaknesses: The randomisation method used (odd and even cow identification numbers) was predictable and therefore open to bias, and no blinding was used. There were differing supportive therapies available to each cow (eg, frequent milking, fluid therapy) and it was unclear whether the uptake of these therapies was significantly different between treatment groups. Some of the assessments made were subjective (eg, estimated quarter milk production). Administration of the second dose of enrofloxacin and some outcome measurements were reliant on owner compliance. No explanation was given for cases that were excluded from the study, and it was also unclear whether the exclusions were balanced across the treatment groups. Large amounts of data were missing and no sample size calculation was performed before data collection took place.