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Title: DEVELOPMENT OF A MODEL FOR USE IN PHARMACEUTICAL TRIALS: INDUCED PASTEURELLA PNEUMONIA AND BODY TEMPERATURE TELEMETRY IN WEANED BEEF CALVES

Author
item FAJT, VIRGINIA
item APLEY, MICHAEL
item Brogden, Kim
item SKOGERBOE, TERRY

Submitted to: American Association of Bovine Practitioners Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 9/15/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The most common method for inducing pneumonic pasteurellosis in cattle for the study of therapeutic and immunologic interventions is to instill fresh live cultures of Pasteurella haemolytica into the trachea, into main stem bronchi, or into the thoracic cavity percutaneously (transthoracic). Evaluating therapeutic outcome may include comparisons of clinical recovery, mortality, weight gain, or other response variables. Our initia goal was to develop a method of inducing pneumonia in weaned beef heifers that consistently produced rectal temperatures of at least 40 C at the time of treatment along with a clinical score of 1 or greater. Inoculation via bronchoalveolar lavage catheter (at the level of the bifurcation of the trachea) using a larger bacterial inoculum produced clinically apparent disease. Lung lesions were of sufficient size and severity to allow comparisons between treatments to be made. Radiotransmitters, placed intravaginally, were used to detect ele3vated body temperatures. The thir component of this model was to determine the feasibility of collecting neutrophils from the lungs in live animals and performing function assays on the collected neutrophils. Initially, relatively few neutrophils could be isolated from bronchoalveolar lavages and transtracheal washes. Those neutrophils isolated were mostly degenerate and non-functional. The collection of neutrophils from the lungs was therefore eliminated from the model. In the subsequent trial, circulating neutrophils were evaluated as an indication of neutrophil function in the lungs. The model was used successfully in a study comparing the efficacy of two antimicrobials in the treatment of respiratory disease. The majority of animals inoculated met the entrance criteria of temperature greater than or equal to 40 C and