Antemortem Diagnosis of Bovine Respiratory Disease

Abstract

The bovine respiratory disease complex (BRDC) is the most common disease problem in feedlot cattle, accounting for 65-75% of feedlot morbidity and mortality. The annual cost of BRDC to the cattle industry has been estimated at $167.2 million to $232.4 million (Perino, 1992). BRDC is caused by a complex interaction of stresses and microorganisms on the host animal. In most outbreaks, it is not possible to diagnose with certainty which infectious agents are present by clinical examination alone. Diagnosis of infectious causes of BRDC has primarily been done on tissue samples obtained from postmortem examinations. This method has resulted in a low diagnosis rate for viral infections. In addition, antibiograms done on bacterial isolates from the lungs of treated dead cattle or chronically ill cattle are of questionable value since these samples were obtained from "treatment failures". We have adopted a new program combining nasal swabs and tracheal swabs to improve viral diagnosis rates and provide more meaningful sensitivity data on bacterial isolates. The goal of this program is to provide more timely and accurate information so informed decisions can be made on treatment, vaccination, and herd health programs when BRDC outbreaks occur.