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

BACKGROUND: Identifying clinical findings that are distinct between inflammatory bowel disease (IBD) and intestinal lymphoma could be helpful for providing preliminary guidance for clients regarding their horse's prognosis while awaiting histopathologic results. HYPOTHESIS/OBJECTIVES: To describe and compare the clinical findings of horses with a final histopathologic diagnosis of IBD vs intestinal lymphoma. ANIMALS: Forty-six adult (≥1-year-old) horses with a final histopathologic diagnosis of IBD or intestinal lymphoma on endoscopic duodenal biopsy, surgical biopsy, or necropsy. METHODS: Retrospective single-center case series via electronic medical record review of histopathology. RESULTS: Eighteen horses had a final diagnosis of lymphoma (11 intestinal only, 7 multicentric including the intestinal tract) and 28 had IBD (22 lymphoplasmacytic IBD, 5 eosinophilic IBD, 1 mixed lymphoplasmacytic and eosinophilic IBD). Acute colic (54%) and recurrent colic (39%) were more common in horses with IBD than in horses with lymphoma (11% and 5%; P = .004 and P = .01, respectively). Ultrasonographic evidence of abdominal mesenteric lymphadenopathy was more commonly identified in horses with lymphoma than horses with IBD (60% vs 0%; P < .001). Clinicopathologic values were largely indistinguishable between groups. CONCLUSIONS AND CLINICAL IMPORTANCE: Clinical findings of IBD and intestinal lymphoma were largely indistinguishable in this cohort, although recurrent or acute colic might be more commonly seen in horses with IBD than those with lymphoma.