Pathological description of naturally occurring Mycoplasma bovis associated pneumonia in bovine calves

Abstract

Mycoplasma bovis is an important etiologic agent of bovine respiratory infection and predominantly causing chronic pneumonic lesion. The present study encompassed standardized pathological, immunohistological and molecular technique for diagnosing natural bovine pneumonic cases with Mycoplasma bovis associated lesions. During the study, examination of 87 carcasses putatively died of pneumonia where Mycoplasma bovis was ascertained in two bovine female calves by immunohistological staining and Polymerase chain reaction. The specific pathological lesions were noted as chronic bronchopneumonia with mild to moderate caseonecrotic lesion and suppurative bronchopneumonia typical of Pasteurella infection. The other bacterial organism associated with these cases was found to be of Pasteurella multocida detected on isolation. No viral etiological association was detected in immunohistological examination in respect of bovine parainfluenza type 3, bovine respiratory syncytial virus and infectious bovine rhinotracheitis virus. The result also revealed that M bovis infection may develop into a severe necrosuppurative bronchopneumonia when associated with high numbers of intralesional organism and into mild catarrhal bronchointerstitial pneumonia when associated with low numbers of organism.