Lesions Associated with Endotoxin Release and Subsequent Mediator Shock

Abstract

Gram-negative organisms are responsible for many diseases of ruminants, including neonatal coliform septicemia, coliform mastitis, salmonellosis, pneumonias caused by Pasteurella spp and Actinobacillus spp, brucellosis, metritis, campylobacteriosis, infections of the cornea and sclera, and thromboembolic meningoencephalitis. Bovine pneumonic pasteurellosis (BPP) is a common respiratory disease in many age groups of cattle. Although the precise mechanism responsible for inducing the exudative fibrinous pleuropneumonia is not understood, other microbial agents and stress predispose cattle to respiratory disease by allowing overgrowth of the normal nasal flora with virulent Pasteurella hemolytica. Although experimental infections with P hemolytica alone can be accomplished, infecting cattle with one of several agents (infectious bovine rhinotracheitis virus, bovine respiratory syncytial virus, parainfluenza-3 virus, and Mycoplasma bovis) increases subsequent to infection with P hemolytica. The pathophysiology of endotoxemia and the subsequent mediator shock will be briefly reviewed as background information for discussing the lesions associated with this disease process.