Study On The Efficacy And Residual Elimination Of Ceftiofur Sodium For Injection In The Treatment Of Bacterial BRD In Cattle

Bovine respiratory disease(BRD)is a common and prevalent disease in cattle,affecting all stages of cattle production and is a major cause of morbidity and mortality in cattle,causing huge losses to the farming industry.Ceftiofur sodium has good efficacy and low drug resistance,and has long been approved for the treatment of BRD abroad,while no relevant trial data for target animals in cattle in China.In order to provide a scientific basis for the use of ceftiofur sodium in cattle,this study was carried out to determine the residual elimination test of ceftiofur sodium for injection in cattle edible tissues and milk,to determine the dose of ceftiofur sodium for injection against naturally infected bacterial BRD(Phase Ⅱ clinical)and to conduct field treatment trials(Phase Ⅲ clinical).In order to investigate the elimination pattern of ceftiofur sodium residues in cattle,a high performance liquid chromatography-tandem mass spectrometry(LC-MS/MS)method was developed for the determination of ceftiofur sodium residues in cattle edible tissues and milk.The results showed that the highest drug concentration of 3772.02μg/kg was found in the kidney tissue of beef cattle at 0.5d after dosing;and the highest drug residue concentration was found in the milk of cows at 10 h after dosing,and the drug concentrations were below the maximum residue limit(MRL)at all sampling points.The MRLs for ceftiofur sodium on bovine edible tissues and milk were calculated for each tissue and milk using the resting period software with reference to the MRLs developed by European Medicines Agency(EMA).The following were found:0 h for the longest dorsal muscle,92.01 h for the injection site,31.77 h for the liver,68.13 h for the kidney,25.74 h for the fat,and 7.148 h for the milk.The results indicate that ceftiofur sodium is eliminated quickly.With reference to the EMA regulations and the practical clinical application,it is recommended that the withdrawal period for ceftiofur sodium for injection in cattle be set at 4 d and the milk abandonment period at 12 h.Phase Ⅱ and Ⅲ clinical trials were completed in this paper in accordance with the requirements of the relevant trials.(1)In a phase Ⅱ clinical trial,60 cattle naturally infected with bacterial BRD were screened and randomly divided into 1.1,2.2,and 4.4 mg/kg·BW injectable ceftiofur sodium(Woruite~?)treatment groups and a 2.2 mg/kg·BW injectable ceftiofur sodium(Tiofur~?)drug control group.15healthy cattle were selected as healthy controls,The therapeutic effect of Woruite~?was evaluated according to the clinical signs,cure rate and bacterial isolation rate of the test cattle.(2)In a phase Ⅲ clinical trial,60 diseased cattle suffering from bacterial BRD were selected for the trial and randomly divided into a 2.2 mg/kg·BW Woruite~?treatment group and a 2.2 mg/kg·BW Tiofur~?drug control group.The therapeutic effect of Woruite~?was evaluated according to the clinical signs,cure rate and bacterial isolation rate of the test cattle.The results show,(1)The cure rates in the 1.1,2.2,and 4.4mg/kg-BW Woruite~?and 2.2 mg/kg·BW Tiofur groups were 46.7%,86.7%,93.3%,and 86.7%,respectively.There was no significant difference(P>0.05)between 2.2,4.4 mg/kg·BW Woruite~?and Tiofur~?drug control groups,all of which had significant treatment effects.(2)The cure rates in the 2.2mg/kg-BW Woruite~?and 2.2 mg/kg·BW Tiofur~?groups were 93.3%and 90.0%,respectively,with no significant difference between the Woruite~?and Tiofur~?groups for bacterial BRD(P>0.05).After 14 d of treatment,no recurrence was observed in successfully treated cattle.Therefore,ceftiofur sodium(Woruite~?)for injection is effective in the treatment of bacterial BRD.The recommended dose is 2.2mg/kg·BW once daily for 3 d,with an additional course of treatment for severe cases.In summary,ceftiofur sodium was effective in the treatment of bacterial BRD.The withdrawal period of ceftiofur sodium in cattle is 4 d and the milk abandonment period is 12 h,and the above results provide a basis for the clinical use of ceftiofur sodium for injection in target animal cattle.