EFFICACY OF FLORFENICOL IN THE TREATMENT OF BOVINE RESPIRATORY-DISEASE - RESULTS OF CLINICAL-TRIALS IN EUROPE

Two hundred and sixty-nine cattle were included in this multicentric E uropean clinical field trial. The cattle, aged 3 to 9 months, exhibite d clinical signs of respiratory disease, including high rectal tempera ture and respiratory rate. They were randomly assigned to either amoxi cillin (N = 133) or florfenicol (N = 136) treatment groups. The animal s were administered intramuscular injections of either amoxicillin (15 mg/kg) of florfenicol (20 mg/kg) on day 0 and day 2 and were clinical ly observed daily for 11 days. From day 11 to day 28, the animals were checked daily by pencheckers and clinically observed by the investiga tor when clinical signs reappeared. All of the 68 Pasteurella isolates obtained from the nasopharyngeal swabs taken on day 0 prior to treatm ent were susceptible to florfenicol, whereas 29 and 22 isolates were e ither resistant or intermediately resistant to chloramphenicol and amo xicillin, respectively. In both the florfenicol and amoxicillin groups , rectal temperature dropped and clinical index improved after treatme nt. However, statistically significant differences in favour of florfe nicol were observed from day 1 to day 10 for rectal temperature and up to day 9 for illness index. During the first 10 days, 2 amoxicillin-t reated cattle died and 64 were considered treatment failures. As a res ult, only 50 percent (67 of 133) of the animals in the amoxicillin gro up were considered treatment successes; during this same period, the s uccess rate in the florfenicol group was much higher, with 85 percent (116 of 136) considered treatment successes. From day 11 to day 28, re lapse or reinfection was seen in 28 percent of the remaining animals i n each group. The difference between the two groups for failure, relap se-reinfection and success rates was highly statistically significant in favour of florfenicol.