Pathomorphological studies of respiratory infections in sheep with special reference to Mycoplasma ovipneumoniae in and around Hassan district

Abstract

Mycoplasma ovipneumoniae is recognized as an important pathogen associated with respiratory disease in sheep, contributing to considerable economic losses in the livestock sector. The present investigation aimed to determine the prevalence of respiratory infections in sheep from the Hassan district and adjoining regions, and to characterize the related pathological changes while confirming the involvement of Mycoplasma ovipneumoniae through molecular analysis. A total of one hundred sheep carcasses were examined, and tissue samples including lungs, trachea, bronchi, bronchioles, and mediastinal lymph nodes were collected for detailed gross, microscopic, and polymerase chain reaction evaluation. Respiratory lesions were observed in seventy-one animals. Molecular detection targeting the GPO3 gene of the Mycoplasma genus revealed infection in 32.39% of samples, and further amplification using species-specific primers for the 16S ribosomal ribonucleic acid gene confirmed Mycoplasma ovipneumoniae in 9.85% of cases. Prominent gross lesions in affected animals included consolidation of the lungs predominantly in cranio-ventral lobes, pulmonary congestion, edema, frothy exudate in the tracheal lumen, and mild fibrinous inflammation of the pericardium. Microscopic examination of pulmonary tissues revealed bronchopneumonia, interstitial pneumonia, and broncho-interstitial pneumonia. Additionally, fibrinous inflammation of the pericardium and depletion of lymphoid tissue in the lymph nodes, indicated systemic involvement associated with respiratory infection. The outcomes of this study confirm the circulation of Mycoplasma ovipneumoniae in sheep within the Hassan district and surrounding areas, highlighting its significant impact on the respiratory system and associated organs.