Comparative Study on Gross and Histopathology in Goat to Experimental Infection with Field Isolates of Mycoplasma

Abstract

Contagious Caprine Pleuropneumonia (CCPP) is a complex respiratory syndrome causing high morbidity and mortality in goats resulting in substantial economic losses in the goat farming. A total of 20 healthy goats were randomly divided into three group’s i-e, (A, B, and C). Each A and B group included 08 animals, while group C contained 04 animals. The animals in group A of about one year of age (with milk teeth), while group B was about two years of age (two permanent incisors). Group C had two animals from each age group. Groups A and B were infected by the intra-tracheal route at the dose of 3×10⁷ CFUs of field isolated Mycoplasma capricolum subspecies capripneumoniae (Mccp) as described by Wesonga et al. (2004) with slight modification. At the same time, the goats in control group C was kept away from the infected animals. Necropsies were performed on animals dying during the course of infection. Among the surviving animals, two goats from group A and B was slaughtered every ten days on days 10, 20, 30, and 40 days post-infection (dpi). Gross lesions in organs like lungs, and trachea were recorded. Tissue samples from the lungs and trachea were collected on days 10, 20, 30 and 40 post-infection (dpi) for histopathological examination. The tissue samples were fixed in 10% formalin, processed, sectioned, and stained with Hematoxylin and Eosin. The tissue slides were examined for any histopathological lesions. Results indicated that gross pathological changes were observed in the trachea and lungs of experimental infected CCPP goats. In trachea, congestion, thin fibrinous mucous plug in lumens, haemorrhage. Purulent exudate, enlarged mesenteric lymph nodes were observed. In lungs, consolidations, enlarged bronchial and medistinal lymph nodes, frothy and fibrinous exudates, thoracic cavities filled with straw-colored fluid, viscous straw colored fluid was found in pleural cavities, multifocal lesions of necrosis and abscess were prominent on lungs surface. Hepatization colours of lungs varying from deep blue to reddish in colour were also observed. Histopathological examination of trachea sections revealed severe CCPP infection. Group A & B plates showed the respiratory ciliated epithelial layer was erupted and erosion of lamina propria in later days of infection. Histopathological examination of lungs sections revealed that in group A, interalveolar capillaries were severely congested, the bronchioles were flooded with fibrinous or serofibrinous exudate, the bronchioles were narrowed by exudate, and the alveolar gaps were filled with fluid. In group B, contagious caprine pleuropneumonia with fibrous tissue mixed with inflammatory infiltration was observed.