Porcine respiratory disease complex, caused by the combined effects of multiple pathogens and various predisposing factors, is a major health problem in modern pig production. Among predisposing factors of environmental origin, mycotoxins present in the diet may play an important role. In this study, we examined the possible synergy between a respiratory pathogen, Mycoplasma hyopneumoniae and fumonisin B1 (FB1) toxin in the porcine respiratory tract. Four groups of pigs (n = 7/ group) were used, one group received a diet containing 20 ppm FB1 toxin from 16 days of age (Group I), a second group infected with M. hyopneumoniae on study day 30 (Group II), and a third group which was both fed FB1 and infected with M. hyopneumoniae (Group III), along with an untreated control group (Group IV). Computed tomography (CT), was applied to follow up the pathological events in the lung. The M. hyopneumoniae infection produced lung lesions in young piglets that were increased by treatment with FB1 toxin. Characteristic pathological findings in FB1 treated pigs (Group I) were remarkable oedema in the lung, slight oedema in the other internal organs, and mild degenerative changes in the kidneys, whereas in the M. hyopneumoniae infected pigs (Group II) catarrhal broncho-interstitial pneumonia was found especially in the cranial and middle lobes and in the cranial third of the caudal lobe of the lung. The pigs in Group III treated with M. hyopneumoniae and FB1 toxin together showed strong oedematous changes in the interstitium of the lung in addition to extended broncho-interstitial pneumonic lesions. In conclusion, dietary exposure to FB1 toxin may complicate or facilitate the course of M. hyopneumoniae infection, and CT proved to be a feasible imaging technique for studying the pathological conditions in the lower respiratory tract of swine.
Financial support of OTKA 81690 is acknowledged.