In order to investigate the bacteriological infection in the respiratory tract, lung lesions were examined in 34 patients (37.77%) from Unnao and 26 cases (28.88%) from Barabanki districts. The identification of thirty-four isolates as Pasteurella spp. was based on their morphology, cultural/colony characteristics, and biochemical properties, such as the production of catalase, urea hydrolysis, citrate consumption, and indole. In Unnao and Barabanki district, emphysematous lung was found in 8 cases (8.88%) and 6 cases (6.66%) of lung lesions, respectively, and congestion with hemorrhagic lesions in 14 cases (15.55%) and 11 cases (12.22%). The lung slaughtered in Unnao and Barabanki district showed two cases (2.22%) of hard nodular growth/granulomatous lesions and one case (1.11%) of nodular lesions. The percentage of cases in each district that had pulmonary oedema was 6 (6.66%) and 5 (5.55%). In both districts during the study period, the highest number of cases of lung congestion and hemorrhages were followed by emphysematous conditions and pulmonary oedema in the slaughtered animal. Microscopic views show that significant emphysema can occasionally be observed in addition to vascular and bronchiolar congestion. The lungs grossly characterized as having pulmonary emphysema upon histopathological investigation showed blood vessel congestion, ruptured alveoli resulting in the creation of giant alveoli. Tissue sections were also stained using the MacCallum-Goodpasture staining procedure in order to demonstrate the organisms, and twenty lung tissues were found to have red coccobaccilli organisms. In pneumonic lungs, mild to moderate fibrosis was seen. Mallory Heidenhain and Masson's trichome staining revealed fibrous tissue as blue. Therefore, because of pasteurellosis, unwell buffaloes are killed in slaughterhouses for human consumption; the flesh from these animals should not be eaten or may be declared ineligible due to illnesses.