Abstract: In order to obtain the optimal therapeutic dosage of ethyl pyruvate (EP) in compound preparation and compare the effects of different concentrations of EP and administration time on treatment outcome,four different mixture ratios of suspensions composed by EP that prepared by Veterinary Medicine Laboratory (Qingdao Agricultural University) were applied to the experimental therapy of mice infected with E.coli. 340 Kunming mice were divided into 17 groups randomly (20 in each group) and then were injected with E.coli ATCC 25922. A ceftiofur (CE) single suspension (CE 5 mg/kg) and four kinds of EP compound suspension (EP was 40,80,120 and 160 mg/kg,respectively) were injected into the mice after 1,4 and 8 h in order to observe the mortality rates of mice and analyze statistically. The results showed that the effect of compound suspension groups of EP 40 and 80 mg/kg were much better than CE single suspension group at 1 and 4 h after vaccination (P<0.05),but there was no significant difference between the two compound suspension groups (P>0.05). At 8 h after vaccination, the therapeutic effect of all compound suspension groups and single suspension group was not significant and there was no significant difference compared to positive control group (P>0.05). The therapeutic effect of compound suspensions of EP 40 and 80 mg/kg were significantly better than CE single suspension, and could help to remarkably improve the cure rate of mice, but there was no significant difference between the two compound suspension groups. It was recommended to choose compound suspension of EP 40 mg/kg from the perspective of security and economy.

Key words: ethyl pyruvate; ceftiofur; E.coli