Abscessing bronchopneumonia in foals - The adequate treatment period and its determination

Abstract

The objective of the present study was to analyse whether a treatment duration of 2 weeks in cases of abscessing bronchopneumonia In foals Is sufficient for a complete recovery without relapses. Antimicrobial treatment with durations of 4 weeks and more for foals Is empirical practice on many farms with endemic foal pneumonia. In the prospective, randomised blind study foals with an abscess score of 15 to 19.5cm (moderate pneumonia) at sonography of the thorax were Included In group 1 (n = 92, treatment: rifampln/tulathromycln). If the abscess score was ≥ 20cm (severe pneumonia), foals were allocated to group 2 (n = 73, treatment: rifampin/azithromycin). The treatment duration (2, 4 or 6 weeks) In groups 1 and 2 depended on the random assignment to these subgroups. Tracheobronchial aspirates from foals with pneumonia were randomly tested for bacterial pathogens by microbiological culture. In enrolled foals clinical examination was done once weekly and WBC counting and ultrasound examination of the lung twice weekly. Foals that required a treatment change because findings worsened or stagnated or the occurrence of another disease, they were taken out of the study (n = 15/165). Such an exclusion of the study was classified as treatment failure and the data from these foals were processed separately until their removal from the study In foals with moderate or severe pneumonia, about 75% recovered after two weeks of treatment and 25% needed longer therapy Clinical signs almost completely regressed during the first two weeks of treatment. The WBC count was not helpful In assessing the course of pneumonia. Three of 150 foals had a recurrence of pneumonia three or more weeks after the end of treatment. The duration of treatment of 2 weeks of moderate and severe abscessing bronchopneumonia seems sufficient In most foals. The younger a foal Is at the day of diagnosis of pneumonia, the more likely It will require more than 2 weeks of therapy or even the treatment will fail. Altogether, the duration of therapy should be tailored to the patient and unnecessary prolonged use of antibiotics can be avoided.