Ultrasonographic progression of lung consolidation after experimental infection with Mannheimia haemolytica in Holstein bull calves

Abstract

Bronchopneumonia (BP) is a disease process that reduces the well-being and economic potential of dairy replacement animals and is a world-wide issue. Clinical signs are variable and frequently inapparent or non-specific, which often results in misclassification of affected animals. Misclassification causes the inappropriate use of antimicrobials and reduces labor efficiency for the operation. At the research level, proper classification is instrumental in achieving an unbiased investigation of the individual animal or whole herd. Thoracic ultrasonography (US), which detects consolidated lung tissue, is a potentially fast and reliable method for diagnosing BP. Studies conducted to determine how quickly lung consolidation develops following bacterial infection by use of antemortem methods, such as thoracic US, are lacking. Results of studies that used postmortem methods suggest that inflammatory infiltrates develop in the lower airways within 2 to 3 hours after infection. Ultrasonography might detect exudate-filled airways equally soon after infection. The purpose of this study was to describe the progression of lung consolidation as determined by US after experimental infection of dairy calves with Mannheimia haemolytica.