Treatment of Bacterial Pneumonia in Feedlot Cattle

Abstract

Pneumonia associated with Pasteurella bacteria is widely acknowledged to be the most important dis-ease of feedlot cattle. In a 13,000-head capacity feedlot in Davis area, uncomplicated bacterial pneumonias were responsible for 42.5% of all deaths over an 18-month period (Table 1). In addition, secondary bacterial pneumonias were a contributing factor in many deaths attributed to infectious bovine rhinotracheitis, bovine viral diarrhea, salmonellosis, cellulitis, paresis and polyarthritis during this same period. Efforts to control these losses were hampered by inadequate information concerning antimicrobic therapy. Consequently, a study of the relationships between the bacteria associated with feedlot pneumonia and the antibiotics used in treatment was initiated. It was hoped that improved knowledge concerning these relationships might permit more precise therapeutic management of the disease. Initial work included microbiologic examination of the pneumonic lesions from 500 lungs. Significant bacterial flora consisted mainly of Pasteurella hemolytica, P. multocida and Corynebacterium pyogenes, alone or in various combinations (Tables 2 and 3). Other bacteria were isolated infrequently. C. pyogenes was isolated infrequently except from chronic lesions (Table 4).