Determining optimal therapy of dogs with chronic enteropathy by measurement of serum citrulline

BACKGROUND: Serum concentration of citrulline is a useful biomarker in human intestinal disease and indicates globally reduced enterocyte mass and absorptive function in various disease states. OBJECTIVES: To determine whether serum citrulline concentration is a biomarker in chronic enteropathy (CE) in dogs, to provide useful information regarding optimal treatment or to predict outcome. ANIMALS: Seventy-four dogs with CE and 83 breed- and age-matched hospital controls with no clinical signs of intestinal disease. METHODS: Retrospective study. Outcome was determined and dogs were categorized by response to treatment as having food-responsive enteropathy (FRE), antibiotic-responsive diarrhea (ARD), or idiopathic inflammatory bowel disease (IBD). Disease severity was quantified by the CIBDAI scoring index. RESULTS: Serum citrulline concentration did not differ between dogs with CE (median, 8.4 µg/mL, 5th-95th percentile 2.0-19.6) and controls (median, 8.1 µg/mL, 5th-95th percentile 2.2-19.7, P = .91). Serum citrulline concentration was similar between dogs with FRE (median, 9.1 µg/mL, 5th-95th percentile 2.0-18.9), ARD (median, 13.0 µg/mL, 5th-95th percentile 1.6-19.2), IBD (median, 8.4 µg/mL, 5th-95th percentile 2.1-21.0; P = .91). Serum citrulline did not correlate to CIBDAI or to serum albumin concentration. CONCLUSIONS AND CLINICAL IMPORTANCE: In our study, serum citrulline concentration was not associated with efficacy of treatment or outcome in dogs with CE.