Haemophilus somnus has repeatedly been reported as an important part of the BRD complex, as well as being incriminated in a general septicemia manifesting itself in laminitis, pleuritis, vascular endothrombosis, enteritis and nephritis. The disease was first described by Colorado researchers in 1956 as infectious thromboembolic meningoencephalitis (TEME). This particular form of the disease is manifested not only in feedlot cattle but in dairy and beef herds. The research that occurred in the isolation and identification of H. somnus as a primary pathogen in cattle and the production of an effective immumzmg agent is considered one of the major breakthroughs in preventing the bovine respiratory disease complex.