Evaluation of duodenal endoscopic and histologic findings, including counts of forkhead box p3-positive regulatory t cells, in dogs with immunosuppressant-responsive enteropathy

OBJECTIVE To prospectively evaluate the clinical and prognostic importance of duodenal endoscopic and histologic findings, including duodenal mucosal counts of forkhead box P3-positive regulatory T cells (Foxp3+ Tregs), in dogs with immunosuppressant-responsive enteropathy (IRE). ANIMALS 57 client-owned dogs with IRE. PROCEDURES The canine chronic enteropathy clinical activity index (CCECAI) was used to assess each dog when IRE was diagnosed (T0) and 1, 3, 6, and 12 months later. Dogs were grouped on the basis of clinical response (responder group vs nonresponder group) and 12-month long-term outcome (responded to treatment and did not relapse [good outcome group] vs did not respond to treatment or had relapsed [bad outcome group]). At T0, dogs underwent gastrointestinal endoscopy and endoscopic biopsy, with results for variables of duodenal endoscopic and histologic evaluations scored and compared across groups. RESULTS At T0, the overall median CCECAI score was 7; CCECAI score was not associated with clinical response or relapse. Dogs had significantly greater odds of being in the bad outcome group (vs the good outcome group) if they had a histologic score of 3 (OR, 3.5; 95% CI, 1.09 to 11.3). No differences in the counts of Foxp3+ Tregs were detected between groups. CONCLUSIONS AND CLINICAL RELEVANCE In dogs with IRE, results indicated that evaluation of Foxp3+ Tregs did not have prognostic value, whereas a duodenal histologic score of 3 could be a negative prognostic factor for response and relapse, and higher severity scores for intraepithelial lymphocytes and lamina propria lymphocytes and plasma cells in duodenal biopsy samples may be negatively associated with response. (Am J Vet Res 2021;82:218–224).