Experimental Actinobacillus pleuropneumoniae challenge in swine: Comparison of computed tomographic and radiographic findings during disease

Computed tomographic (CT) findings during the course of App challenge were verified by radiological imaging, clinical, serological, gross pathology and histological examinations. Findings from clinical examinations and both CT and radiological imaging, were recorded on day 7 and day 21 after challenge. Clinical signs after experimental App challenge were indicative of acute to chronic disease. Lung CT findings of infected pigs comprised ground-glass opacities and consolidation. On day 7 and 21 the clinical scores significantly correlated with the scores of both imaging techniques. At day 21, significant correlations were found between clinical scores, CT scores and lung lesion scores. In 19 out of 22 challenged pigs the determined disease grades (not affected, slightly affected, moderately affected, severely affected) from CT and gross pathological examination were in accordance. Disease classification by radiography and gross pathology agreed in 11 out of 24 pigs.High-resolution, high-contrast CT examination with no overlapping of organs is superior to radiography in the assessment of pneumonic lung lesions after App challenge. The new CT scoring system allows for quantification of gross pathological lung alterations in living pigs. However, computed tomographic findings are not informative of the etiology of respiratory disease.For decades, respiratory tract diseases in pigs have led to high economic losses in pig producing countries. Acute disease outbreaks can often be immediately diagnosed based on the detection of clinical signs by farmers and veterinarians, while chronic and subclinical respiratory disorders are difficult to diagnose. In cases with chronic disease, gross pathology at abattoir slaughter provides the only indication of disease presence. In contrast to many diagnostic methods available for detecting bacterial and viral respiratory pathogens in samples of living pigs, methods to diagnose the extent of lung lesions in chronically diseased animals,