REGIONAL DANOFLOXACIN LUNG-TISSUE CONCENTRATIONS AND THEIR RELATIONSHIP TO REGIONAL PULMONARY BLOOD-FLOW IN CONSOLIDATED AND NONCONSOLIDATED BOVINE LUNG

Six calves with areas of pulmonary consolidation attributable to bronc hopneumonia, and 6 calves with no areas of consolidation were given IV injections of danofloxacin. This injection was followed approximately 55 minutes later by injection of 15-mum radiolabeled microspheres to measure regional pulmonary blood flow. Calves were euthanatized exactl y 1 hour after the danofloxacin injection. Six samples for determinati on of danofloxacin concentration, each surrounded by 4 samples for det ermination of gamma emission counts, were taken from each lung. Additi onal samples focusing on the line of demarcation between consolidated and nonconsolidated tissue were taken from calves with pulmonary conso lidation.Data from calves with no areas of pulmonary consolidation ind icated that blood flow was significantly reduced in the caudodorsal po sition of the left lung and the caudodorsal and cranioventral position s of the right lung, compared with that in other positions within the lungs. Danofloxacin concentrations in the cranioventral positions of t he right and left lungs were significantly lower than those in the mid dle-dorsal positions. Differences in danofloxacin concentrations and b lood flow were analyzed in consolidated and non-consolidated cranioven tral and middle-ventral positions of the lungs from calves with pulmon ary consolidation. Decreases in blood flow in consolidated lung tissue ranged from 83.3 to 91.7%. Danofloxacin concentrations in consolidate d lung tissue were significantly reduced by 41% in the middle-ventral position of the left lung. The line of demarcation step study revealed a significant reduction of blood flow at 2 and 4 cm into consolidated lung tissue, with reductions of 84 and 88%, respectively. Danofloxaci n concentration did not significantly decrease in consolidated tissue.