Acute Colitis in Horses

Overview

• Acute colitis causes rapid debilitation and death in horses.
• Untreated horses have a high mortality rate (>90%), but appropriate treatment can lead to gradual recovery over 7 to 14 days.
• Characterized by diarrhea, endotoxemia, leukopenia, and hypovolemia.
• Affects horses aged 2 to 10 years, with sudden onset and rapid progression.
• Often preceded by stress; definitive diagnosis is rare (~20% of cases).

Pathophysiology and Clinical Signs

• Diarrhea results from abnormal fluid and ion transport in the intestines.
• Leads to severe dehydration and electrolyte imbalances, potentially causing death.
• Caused by inflammation of the cecum (typhlitis), colon (colitis), or both (typhlocolitis).
• Distinctive features in horses include high mucosal prostaglandin concentrations and intense inflammation.

Causes and Diagnostic Characteristics

• Salmonella spp: Identified via bacterial culture or PCR.
• Clostridium spp: Identified by feces content and cytotoxin testing.
• Neorickettsia risticii: Identified by seasonal/geographic patterns and PCR.
• Parasite Infestations: Related to inadequate deworming.
• NSAID Toxicity: Slow onset with specific symptoms.
• Antimicrobial Use: History of antimicrobial administration.
• Arsenic Poisoning: Marked symptoms and rapid progression.
• Other Causes: Includes Cantharidin toxicosis, colitis X, and sand ingestion.

Clinical Evaluation

• Symptoms include lethargy, inappetence, colic, and liquid feces.
• Requires early veterinary intervention as it can be life-threatening.

Laboratory Tests

• Blood tests help determine disease severity and fluid needs.
• Common findings include neutropenia, electrolyte imbalances, and azotemia.

Treatment

• Fluid Therapy: Key to treatment; involves intravenous fluids to restore plasma volume.
• Colloid Replacement: Addresses decreased plasma protein.
• Antiendotoxin Therapy: Essential to prevent complications like laminitis.
• Antiinflammatories and Analgesics: Nonsteroidal drugs like flunixin meglumine are used.
• Antimicrobials: Used judiciously, especially in cases of N risticii colitis.
• Antisecretory Agents: Currently ineffective for large bowel diarrhea.
• Nutritional Management: Encourages intake of quality hay and feed.

Recovery and Prognosis

• Prompt treatment improves prognosis, but deterioration can occur rapidly.
• Horses with persistent severe symptoms have a poor prognosis.
• Frequent complications include laminitis and significant weight loss.

Suggested Readings

• Various studies and articles provide deeper insights into equine colitis and associated treatments.

These notes provide a comprehensive summary of acute colitis in horses, covering pathophysiology, diagnostic criteria, treatment strategies, and prognosis. The information is useful for veterinary studies and practical application in equine health management.