Effect of aerial ammonia on porcine infection of the respiratory tract with toxigenic Pasteurella multocida
Andreasen, M.; Baekbo, P.; Nielsen, J.P.
Acta Veterinaria Scandinavica 40(3): 197-203
1999
ISSN/ISBN: 0044-605X PMID: 10605136 Document Number: 498492
Two groups of 5 pigs each were continuously exposed to 50 ppm ammonia and <5 ppm ammonia (control), respectively, for a 59-day period (from 37 kg to 90 kg bodyweight) followed by necropsy. In an aerosol chamber, all pigs were exposed to an aerosol of toxigenic P. multocida type A (mean bacterial concentration in the aerosol-exposure chamber: 105 colony forming units/msuperscript 3; exposure period: 25 min) at day 10, 21, 35 and 49 after the onset of ammonia exposure. During the experiment none of the pigs showed clinical signs of pneumonia nor did they develop visible distortion of the snout. None of the pigs had gross lesions in the lungs at necropsy and toxigenic P. multocida was not detected by culture from the lungs from any of the pigs. The chance of recovering toxigenic P. multocida from nasal swabs (collected during the experiment) was 2-4 times greater in the test group compared to the control group. The average daily weight gain was lower for the ammonia exposed pigs compared to the control group. It is concluded that ammonia at a concentration of 50 ppm is unlikely to predispose growing pigs to pulmonary infection with toxigenic P. multocida.