Utility of the combined use of 3 serologic markers in the diagnosis and monitoring of chronic enteropathies in dogs

BACKGROUND: Dogs with chronic enteropathies (CE) displayed elevated IgA seropositivity against specific markers that can be used to develop a novel test. OBJECTIVE: To assess a multivariate test to aid diagnosis of CE in dogs and to monitor treatment‐related responses. ANIMALS: One hundred fifty‐seven dogs with CE/inflammatory bowel disease (IBD), 24 dogs non‐IBD gastrointestinal disorders, and 33 normal dogs. METHODS: Prospective, multicenter, clinical study that enrolled dogs with gastrointestinal disorders. Serum sample collected at enrollment and up to 3 months follow‐up measuring OmpC (ACA), canine calprotectin (ACNA), and gliadin‐derived peptides (AGA) by ELISA. RESULTS: Seropositivity was higher in CE/IBD than normal dogs (66% vs 9% for ACA; 55% vs 15% for ACNA; and 75% vs 6% for AGA; P < .001). When comparing CE/IBD with non‐IBD disease, ACA and ACNA displayed discriminating properties (66%, 55% vs 12.5%, 29% respectively) while AGA separated CE from normal cohorts (54% vs 6%). A 3‐marker algorithm at cutoff of ACA > 15, ACNA > 6, AGA > 60 differentiates CE/IBD and normal dogs with 90% sensitivity and 96% specificity; and CE/IBD and non‐IBD dogs with 80% sensitivity and 86% specificity. Titers decreased after treatment (47%‐99% in ACA, 13%‐88% in ACNA, and 30%‐85% in AGA), changes that were concurrent with clinical improvements. CONCLUSION AND CLINICAL IMPORTANCE: An assay based on combined measurements of ACA, ACNA, and AGA is useful as a noninvasive diagnostic test to distinguish dogs with CE/IBD. The test also has the potential to monitor response to treatment.