Comparison of the efficacy of rifampin/azithromycin and rifampin/tulathromycin for the treatment of foals affected with pneumonia

Abstract

SummaryBackgroundThere is a lack of data on treatment protocols of moderate to severe pneumonia in foals.ObjectivesThe aim of the study was to compare the effectiveness of two antibiotic combinations, rifampin/azithromycin and rifampin/tulathromycin, and to find out which one leads to faster healing of pulmonary abscesses in foals and long‐term treatment success.Study designThe study was designed as a prospective, randomised and blind study.MethodsA total of 160 foals older than 4 weeks of age with moderate to severe pneumonia from a Warmblood stud were included in the study. An abscess score of ≥15 cm was chosen as the start of treatment to rule out possible spontaneous healing of foals with ultrasonographic pulmonary findings. Foals with moderate to severe pneumonia were randomly assigned to one of two groups and treated with different antibiotic combinations. The foals assigned to group R/T (n = 87) were treated with rifampin (10 mg/kg orally once daily) and tulathromycin (2.5 mg/kg dose once weekly intramuscularly/intravenously). The foals in group R/A (n = 73) were treated with rifampin and azithromycin (each 10 mg/kg orally once daily). The effect of treatment was evaluated twice weekly based on the findings of the clinical examination and the sonographically determined abscess score. Additionally, the white blood cell count of the foals was determined once weekly.ResultsThe recovery rates (group R/T 89.6% and group R/A 91.7%) did not differ significantly between treatment groups. Most foals needed 3 weeks of treatment to recover.Main limitationsAs the pneumonia was diagnosed in an early stage, it is questionable whether the results can be transferred to clinical cases with more severe lesions.ConclusionIn our study population, both antimicrobial combinations were effective in treating foals with moderate to severe bronchopneumonia in 3 weeks of time.