Pathology of Pasteurella Multocida Infection in Chickens

The present study was conducted on 42, 12-15 weeks old birds to study the gross and histopathological changes induced by Pasteurella multocida infection. The birds were divided into two groups viz., control and infected consisting of 21 birds each. The birds in infected group were administered with LD 50 of local isolate of Pasteurella multocida A:1. Three birds from each group were randomly sacrificed and subjected to thorough post mortem examination. Tissues were collected in 10% buffered formalin for histopathological studies. Initially pathological lesions were of acute septicaemic nature, congestion, hemorrhage and presence of bacterial colonies. Later on fibrinous pericarditis, necrosis of liver and kidney and lymphoid depletion and RE cell hyperplasia in the spleen were observed. Present address: 1 Department of Veterinary Pathology, SKUAST, Jammu. INTRODUCTION Fowl cholera is a septicaemic bacterial disease of poultry. It is one of the earliest reported diseases of chicken caused by Gram negative Pasteurella multocida and is characterized by high mortality. The outbreaks of this disease have been reported in India from time to time and more so in the recent past (Char et al., 1982; Ramadevi et al., 2000). Currently, the disease has reemerged as a major cause of economic losses to the poultry industry all over the world. Therefore, the present study was undertaken to study pathology and pathogenesis of a local isolate of P. multocida in chickens. MATERIAL AND METHODS In the present study, a total of 42, 1215 weeks old disease free white Leghorn birds were kept under strict hygienic conditions. They were given commercial layer ration and boiled drinking water ad lib. They were divided into two groups viz. control group (Group-I) and infected group (Group-II) consisting of 21 birds each. The infected group was administered LD 50 (1.8 x 10 CFUs) of local isolate of P. multocida serotype A:I intravenously. The control group was administered with equal amount of plain sterile BHI broth @ 0.2 ml I/V. Three birds from each group were slaughtered at 12 hours, 1 day, 2 days, 5 days, 7 days, 10 days and 15 days post infection (DPI). Detailed post-mortem was conducted on sacrificed birds and gross lesions if any, were recorded. The tissues namely liver, heart, kidneys, lungs, spleen, brain, ovaries, pancreas, proventriculus and oesophagus were collected in 10% buffered formalin and processed for H and E staining. RESULTS AND DISCUSSION Grossly the birds in infected group revealed lesions like congestion of lungs, liver, spleen, kidney and heart and petechial/ eccymotic hemorrhages on the surface of heart in early stages (Fig. 1). Later on pericardium showed fibrinous pericarditis. The liver and spleen revealed mottling and congestion, splenomegaly and occasionally necrotic foci in liver. Hemorrhages were also observed on the junction of oesophagus and proventriculus and occasionally on proventriculus only. Kidneys reveal edema and ovaries also revealed congestion initially. Conjunctivitis was also observed during the later half of the experiment. These changes have also been Indian J. Anim. Res., 40 (1): 15 19, 2006