Correlation of microbiological and histological findings in bovine fibrinous pneumonia.

In a retrospective morphological and microbiological study, 39 of 55 cases of bovine fibrinous pneumonia were diagnosed as fibrinous pleuropneumonia. Twenty-nine of these 39 (74%) were associated with Pasteurella hemolytica, but only two cases (5%) with P. multocida. In contrast, of the 16 cases classified as fibrinous bronchopneumonia, one (6%) was associated with P. hemolytica, and nine (56%) with P. multocida. In eight cases Mycoplasma and Hemophilus somnus were found in association with either P. hemolytica or P. multocida but were never isolated alone. We concluded that the use of the term pasteurellosis, implying Pasteurella as the cause, is imprecise because lesions associated with P. hemolytica fulfill the criteria of a fibrinous pleuropneumonia, whereas P. multocida is more likely to cause a bronchopneumonia with moderate amounts of fibrin.