Clinicopathological studies on respiratory affections in small ruminants with special reference to Mycoplasma species

Abstract

Pneumonia is a major health concern in small ruminants, significantly reducing productivity and causing substantial economic
losses worldwide. Mycoplasma species are key pathogens implicated in respiratory infections of goats and sheep, acting either
alone or in combination with other microbes. This study investigated haematological changes and identified major respiratory
pathogens in clinically affected small ruminants. It also evaluated the pathological and immunohistochemical changes associated
with Mycoplasma induced pneumonia in dead animals. A total of 50 animals (42 goats and 8 sheep) showing respiratory signs
were examined. Blood and nasal swab samples were collected to assess haematological parameters and identify causative agents.
Haematological analysis revealed significantly elevated total leukocyte counts and neutrophilia (P<0.05) in affected animals, along
with a slight increase in lymphocytes, indicating an active inflammatory process. Bacterial culture of nasal swabs identified Staphylococcus spp. (50%) as the most common isolate, followed by E. coli (30%) and Streptococcus spp. (10%). Postmortem examination
of 19 goats with respiratory illness revealed gross lung changes, including consolidation, mucopurulent discharge and tracheal
congestion. Histopathological evaluation confirmed interstitial pneumonia in 11 (57.89%) animals, characterized by inflammatory
infiltrates, alveolar septal thickening. The presence of mixed inflammatory cell populations suggested both acute and chronic
phases of disease. Immunohistochemical analysis confirmed the presence of Mycoplasma antigens in all 11 histopathologically
positive cases. In conclusion, Mycoplasma associated pneumonia, often compounded by secondary bacterial infections, plays a
significant role in the respiratory disease complex of small ruminants. Early diagnosis, along with improved management and
control measures is essential to reduce economic losses in small ruminant production systems.