Differentiation between five types of pneumonia distribution pattern in pigs

Five types of lesion distribution pattern in pig pneumonia were described through gravity point calculation on the lesions of abattoir samples of pig lungs, using the gravity points as the matrix for a statistical characterisation of the type. The pneumonia types studied were: bronchopneumonia, pleuropneumonia, secondary disseminated bronchopneumonia, vermoid disseminated pneumonia and haematogenically disseminated (embolic) pneumonia. A qualitative approach to pneumonia type designation by pathological and microbiological examination was not consistent with the quantitative description, as the pathological features and the isolated microorganisms varied between cases of a type. Of the five types studied only two types (pleuropneumonia and vermoid pneumonia) were not distinguishable from each other in a type to type comparison. The patterns observed reflect two main pathways of disease dispersion in pulmonary disease, bronchogenic and haematogenic. The haematogenically dispersed pneumonia had a random lesion distribution pattern, while the bronchogenic type patterns were skewed. Some patterns were shown to reflect properties of the dispersive system and vehicle, while the lesion distribution determinants of pleuropneumonia and vermoid pneumonia need further study. The two major dispersion pathways could be distinguished with high levels of confidence from each other by a simple calculation: the number of lesions in the lobi apicales et cardiaci expressed as a percentage of the total number of lesions.