NAVLE Multisystemic

Equine Endotoxemia Study Guide

Endotoxemia is a life-threatening systemic inflammatory condition resulting from the presence of bacterial endotoxin (lipopolysaccharide, LPS) in the bloodstream.

Overview and Clinical Importance

Endotoxemia is a life-threatening systemic inflammatory condition resulting from the presence of bacterial endotoxin (lipopolysaccharide, LPS) in the bloodstream. It remains one of the leading causes of mortality in horses and is intimately involved in the pathogenesis of gastrointestinal disorders causing colic, neonatal foal septicemia, retained placenta, pleuropneumonia, and other gram-negative infections.

Horses are exquisitely sensitive to endotoxin compared to other species, with circulating concentrations as low as 0.01 ng/mL capable of producing clinical signs. This heightened sensitivity makes early recognition and aggressive treatment essential for survival.

High-YieldOn the NAVLE, endotoxemia questions frequently appear in the context of colic cases (especially strangulating lesions), colitis, retained placenta in mares, and neonatal sepsis. Always look for the classic clinical triad: tachycardia, tachypnea, and abnormal mucous membrane color (brick-red, cyanotic, or presence of a toxic line).
Source Category Clinical Examples
GI Tract (Most Common) Strangulating intestinal lesions, colitis, enteritis, proximal enteritis/anterior enteritis, grain overload, large colon volvulus
Reproductive Retained fetal membranes (greater than 3 hours post-foaling), postpartum metritis, placentitis
Respiratory Pleuropneumonia, bacterial pneumonia
Neonatal Neonatal septicemia, failure of passive transfer, omphalitis
Other Peritonitis, severe wounds/cellulitis, bacteremia from any source

Etiology and Pathophysiology

Structure of Endotoxin (LPS)

Lipopolysaccharide (LPS) is the major structural component of the outer membrane of gram-negative bacteria. It consists of three distinct regions:

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