Evaluation of novel serological markers and autoantibodies in dogs with inflammatory bowel disease

BACKGROUND: The use of serological markers to diagnose inflammatory bowel disease (IBD) in humans is well‐established. Because of the frequency of IBD in dogs and resources required for its diagnosis with current methods, new approaches are desired. OBJECTIVE: The goal is to evaluate novel serologic markers to differentiate clinical cohorts in dogs with gastrointestinal (GI) disease and assess their potential to develop a serum‐based IBD diagnostic test. ANIMALS: Seventy dogs diagnosed with biopsy‐confirmed IBD, 23 dogs with non‐IBD predominantly acute GI diseases, and 58 normal dogs. METHODS: Prospective control study. ELISA methods were developed to detect autoantibodies to polymorphonuclear leukocytes (APMNA) and calprotectin (ACNA), antibodies against gliadins (AGA), microbial outer membrane porin C (ACA), and flagellins (AFA) isolated from diseased dogs based on clinical and histopathological scoring. RESULTS: IBD dogs displayed a 39%‐76% prevalence of seropositivity against selected serologic markers that markedly decreased to 0%‐13% in non‐IBD and normal dogs. ROC analysis showed statistical significance in differentiating the cohorts, with seropositivity against OmpC being the highest single performance marker. The combination of markers such as OmpC and APMNA reached specificities of 93%‐99% and 79%‐98% and sensitivities of 76%‐97% and 66%‐86% when comparing IBD versus normal cohorts and non‐IBD cohorts, respectively. CONCLUSION AND CLINICAL IMPORTANCE: Seropositivity of canine immunoglobulins A against selected serologic markers in dogs appears promising in the detection and differentiation of IBD versus other acute GI conditions. Among them, antibody reactivity to Escherichia coli OmpC and canine autoantibodies against polymorphonuclear leukocytes displayed the highest single marker discriminating performance.