At the end of the experiment, whichwas four days after
aerosol exposure, the pigs were euthanized by intravenous
injection of a pentobarbiturate followed by exsanguination
and necropsy. Gross pathology findings were
recorded in regard to type and size of lesion on lung
drawings and lungs were weighed and relative lung
weights were calculated as percentage of the body
weight. The affected proportion of the lungwas estimated
from the size of the lesion in the lung drawing. Tissue
samples fromtwo prior defined lung locations were taken
from all pigs for histological and bacteriological examinations.
In case lesions were outside the standard
location a third sample from this location, was taken.
Bronchial lymph nodes were collected from all pigs for
histological and bacteriological examinations. Specimens
were cultured to determine the presence of A. pleuropneumoniae
and to confirm the serotype as previously
described