bacteriological and therapeutic studies on mannheimia haemolytica and pasteurella multocida in bovine respiratory disease at dairy cattle farms in tehran

in this study, we performed a bacteriological investigation on bovine respiratory infections. additionally, the study evaluates the efficacy of florfenicol 30 µg produced by rooyan darou company (test group) as compared to a similar drug produced by aboraihan company (control group). sampling was carried out on 30 calves at two farms with 30-55% incidence rate of respiratory disorders. nasopharyngeal swabs were collected for culture, biochemical activity, and antibiograme testing from all the calves before commencing the treatment. the calves of the test group received florfenicol 30 µg (20 mg/kg, two intramuscular [im] injections with a 48-hour interval). similarly, the control group received the same drug dose produced by aboraihan company. all the calves were examined clinically before treatment, and ultimately, clinical index score was recorded for each calf based on observation gradings on days two, four, and seven after the treatment. the results of culture analysis and routine bacteriological techniques indicated that mannheimia haemolytica and pasteurella multocida were isolated as dominant bacteria, and the antibiogram test emphasized sensitivity to florfenical 30 µg. the results indicated a significant reduction in the mean total value index in both groups after the treatment (p≤0.05), and changes of the total value index showed no significant differences between the two groups (p≥0.05), indicating that both antibiotics have the same effect on resolving clinical signs and the treatment of respiratory infection.