THE CLINICAL EFFICACY OF ENROFLOXACIN IN THE TREATMENT OF EXPERIMENTAL BOVINE PNEUMONIC PASTEURELLOSIS

The clinical efficacy of enrofloxacin was tested in carves with experi mentally induced pneumonic pasteurellosis. A strain of Pasteurella hae molytica, biotype A, serotype 1 (P. haemolytica Al), which had been is olated from an outbreak of pneumonic pasteurellosis in feedlot calves, was used to induce the disease in 24 eight-month-old calves. Each ani mal received, by intratracheal injection, 6 x 10(11) colony forming un its of P. haemolytica Al in a four-hour log phase culture. Twelve simi lar animals were kept as non-infected controls (Negative Control group ). Treatment of the infected animals commenced 40 h after infection an d was as follows: 12 animals each received 2,5 mg/kg enrofloxacin subc utaneously and 12 animals each received 5 ml sterile saline intramuscu larly (Positive Control group). All treatments were given once daily f or three consecutive days. Clinical examinations were performed on all animals once daily, starting prior to infection and continuing until 12 d post-infection. The parameters evaluated were rectal temperature, habitus (attitude), ocular mucous membrane congestion and abnormal so unds on lung auscultation. On day14 post-infection, all animals were k illed and their lung lesions (if any) estimated as the percentage invo lvement of each pair of lungs. The only statistically significant (P g reater than or equal to 0,05) differences observed were between the Ne gative Control group and the Positive Control group. Noticeable differ ences were seen between the enrofloxacin-treated group and the Positiv e Control group, but they were not statistically significant (P> 0,05) . The average lung lesion score (pneumonic lesions as a percentage of total lung volume) for the Positive Control group was 12,1 % and that of the enrof loxacin-treated group, 8,4%. This difference was not stat istically significant (P> 0,05).