Bovine Respiratory Disease (BRD) complex as a signal for Bovine Viral Diarrhea Virus (BVDV) presence in the herd

ABSTRACT

Background: Infections are caused by Bovine Viral Diarrhea Virus and still continue to be a worldwide plague in cattle industry. It is responsible for sudden death syndromes in adult cattle with high mortality rates, abortions, acute gastrointestinal and respiratory diseases. The BVDV infection occurs in early pregnancy (40-142 days), in immunosuppressed females or cows results in 100% of persistently infected (PI) calves that are seronegative and asymptomatic at birth. Evidences suggests that BVDV contributes to BRD complex potentiating secondary infections caused by Mannheimia haemolytica e Pasteurella multocida due to its immunosuppressive action. However, the farmers have often associated the respiratory syndrome with other infectious agents. This paper reports the attendance of dairy calves manifesting clinical signs of bronchopneumonia, which led to the screening of the persistently infected animals to control of the BVDV infection in the herd. Materials, Methods & Results: During the technical assistance, ten calves manifesting bronchopneumonia were selected to trans-tracheal lavage (TL) in order to identify possible infectious agents. Reverse transcription polymerase chain reaction (RT-PCR) detected the presence of BVDV in two heifers. Pasteurella multocida was the unique bacterial agent isolated from TL (5/10, 50%). These data motivated the technical team and [...](AU)