LAUSR

BACKGROUND Idiopathic acute hemorrhagic diarrhea syndrome (AHDS) is characterized by acute onset of bloody diarrhea, severe dehydration, and increased vascular and intestinal mucosal permeability. Markers of gastrointestinal inflammation, protein loss, and changes in the intestinal microbiota have not been studied extensively in dogs with AHDS. KEY FINDINGS For 3 consecutive days, feces were collected from dogs with AHDS, and assayed for calprotectin and S100A12 (both markers of inflammation), α1 -proteinase inhibitor (a marker of gastrointestinal protein loss), and the presence of selected species of bacteria. Concentrations of all assayed markers were significantly greater than the institutional reference intervals at the time of presentation, and all decreased significantly by Day 3 of treatment. Abundances of selected bacterial groups (Ruminococcaceae, Faecalibacterium spp., Bifidobacterium spp., and Proteobacteria) at the time of diagnosis were consistent with an intestinal bacterial dysbiosis. No differences in the abundance of bacterial groups over time was seen, except for a mild but significant decrease in Ruminococcaceae at Day 3. SIGNIFICANCE These results suggest that canine AHDS is associated with a significant but transient gastrointestinal loss of protein and intestinal inflammation. The intestinal bacterial dysbiosis appears to outlast the protein loss and inflammation.