Equine Acute Colitis and Diarrhea Study Guide

Overview and Clinical Importance

Acute colitis represents one of the most life-threatening gastrointestinal emergencies in equine practice. It is characterized by inflammation of the large intestine (cecum and colon) resulting in profuse diarrhea, dehydration, electrolyte derangements, and endotoxemia. The mortality rate ranges from 25-42% even with aggressive treatment, making rapid diagnosis and intervention critical for survival.

Salmonella spp. and Clostridium spp. (including Clostridioides difficile and Clostridium perfringens) are the most common infectious bacterial causes of acute colitis in horses. These pathogens carry significant zoonotic potential and biosecurity implications, particularly Salmonella, making appropriate isolation protocols essential.

Etiology and Pathogen Characteristics

Salmonella Species

Salmonella enterica is a Gram-negative, facultative anaerobic rod belonging to the family Enterobacteriaceae. It is the most common infectious cause of diarrhea in horses and poses significant zoonotic risk.