Vet. Res. 35 (2004) 309-324
DOI: 10.1051/vetres:2004012

Pathophysiological changes occurring during Escherichia coli endotoxin and Pasteurella multocida challenge in piglets: relationship with cough and temperature and predicitive value for intensity of lesions

David J. Halloy^a, Sandrine Bouhet^b, Isabelle P. Oswald^b, Michèle Goret-Nicaise^c, Marylène Kobisch^d, Jacques Mainil^e and Pascal G. Gustin<sup>a

a</sup>  Department of Functional Sciences, Unit of Pharmacology, Pharmacotherapy and Toxicology, Faculty of Veterinary Medicine, University of Liège, Boulevard de Colonster B-41 4000 Liège, Belgium
^b  INRA, Unit of Pharmacology and Toxicology, BP 3, 31931 Toulouse Cedex, France
^c  Human Anatomy Research Unit, Faculty of Medicine, Catholic University of Louvain (UCL), Brussels, Belgium
^d  AFSSA, Laboratory of avian and swine research, Unit of mycoplasmology and Bacteriology, BP 53, 22440 Ploufragan, France
^e  Department of Infectious and Parasitic Disease, Unit of Bacteriology, Faculty of Veterinary Medicine, University of Liège, Boulevard de Colonster B-43 4000 Liège, Belgium

(Received 2 May 2003; accepted 30 January 2004)

Abstract - The aims of this study were (1) to correlate cough and body temperature (BT) with the severity of bronchopneumonia in pigs, (2) to determine whether these clinical signs can be used to early diagnose bronchopneumonia and (3) to assess the predictive values of cough and BT regarding lung lesions. Bronchopneumonia was induced by administering E. coli endotoxin (LPS) combined with Pasteurella multocida type A (PmA) in the trachea of 13 piglets. Saline-instilled negative controls (n = 8), PmA inoculated (n = 6) and LPS instilled (n = 5) groups were also constituted. Cough and BT were recorded daily while the bronchopneumonia severity was assessed using bronchoalveolar lavage fluid (BALF) cytology, cytokines and measurement of lung lesion volume. Changes in expiratory breathing pattern were also measured (Penh). The combination of LPS and PmA induced a subacute bronchopneumonia characterised by macrophage, neutrophil, and lymphocyte infiltration, changes in Penh and an increase in the mRNA level of IFN- while IL8, IL-18 and TNF- mRNA levels remained unchanged. The daily body weight gain of infected animals was significantly reduced. Cough and BT changes were proportional to the intensity of the lung inflammatory process, functional respiratory changes and to the extent of macroscopic lesions. When comparing the individual values of cough and BT to thresholds defined for both parameters, an early diagnosis of pneumonia was possible. Considering the pooled data of each group, it was possible to define thresholds allowing an early segregation between the groups of diseased and healthy piglets. The daily values of cough and BT were predictive for the volume of lung lesions recorded at the end of the trial. In conclusion, cough and BT appear as potential indicators for the intensity and the evolution of the respiratory disease. They also seem to be good predictors for the magnitude of lung lesions and weight gain recorded at the study endpoint.

Key words: lipopolysaccharides / bronchopneumonia / breathing pattern / whole body barometric plethysmography / cytokines

Corresponding author: Pascal G. Gustin P.Gustin@ulg.ac.be

© INRA, EDP Sciences 2004