Use of clinical findings to distinguish between intestinal lymphoma or inflammatory bowel disease in horses.

Overview

• This study investigated how clinical signs can help differentiate between inflammatory bowel disease (IBD) and intestinal lymphoma in horses before definitive histopathology results are available.
• It aimed to identify distinct clinical features that could guide prognosis and treatment decisions while awaiting biopsy confirmation.

Background and Importance

• Inflammatory bowel disease (IBD) and intestinal lymphoma are both serious conditions affecting the equine gastrointestinal tract.
• Diagnosing these diseases definitively requires histopathologic examination of tissue biopsies, which can be time-consuming.
• Early clinical differentiation could provide useful preliminary guidance for veterinarians and horse owners regarding prognosis and management.

Study Objective

• To describe and compare the clinical signs and diagnostic findings of horses ultimately diagnosed with IBD versus intestinal lymphoma based on biopsy or necropsy results.

Methods

• Retrospective review of medical records at a single veterinary center.
• Included 46 adult horses (age ≥1 year) with confirmed histopathologic diagnosis of either IBD or intestinal lymphoma using endoscopic duodenal biopsies, surgical biopsies, or post-mortem examination.
• Compared clinical signs, ultrasonographic findings, and lab test results between the two groups.

Results

• Among the 46 horses:
  • 18 diagnosed with lymphoma (11 with intestinal lymphoma only, 7 with multicentric lymphoma including intestines)
  • 28 diagnosed with IBD (22 lymphoplasmacytic IBD, 5 eosinophilic IBD, 1 mixed type)
• Clinical signs:
  • Acute colic was reported more frequently in horses with IBD (54%) compared to those with lymphoma (11%) — statistically significant difference (P = .004).
  • Recurrent colic was also more common in IBD horses (39%) versus lymphoma horses (5%) — statistically significant (P = .01).
• Ultrasonography:
  • Mesenteric lymphadenopathy (enlarged abdominal lymph nodes) was detected in 60% of horses with lymphoma but in none of the IBD cases (P < .001).
• Clinicopathologic tests (bloodwork, etc.) showed largely overlapping results between IBD and lymphoma groups, making them unreliable for differentiation.

Conclusions and Clinical Implications

• Most clinical findings are similar between IBD and intestinal lymphoma in horses, limiting their utility for early differentiation.
• The presence of acute or recurrent colic tends to favor IBD over lymphoma as a diagnosis.
• Ultrasonographic identification of mesenteric lymphadenopathy strongly suggests lymphoma.
• Clinicopathologic data alone is insufficient to distinguish these diseases.
• While histopathology remains the gold standard for diagnosis, attention to colic patterns and ultrasound findings can help guide provisional clinical impressions and discussions about prognosis.

Summary

• This study highlights that although few clinical clues distinguish intestinal lymphoma from IBD in horses, the presence of specific symptoms (colic episodes) and use of ultrasound to detect lymph node enlargement may assist veterinarians before biopsy confirmation.
• Early clinical suspicion based on these findings may improve case management and client communication while awaiting definitive diagnosis.