Circulating markers of endothelial activation in canine parvoviral enteritis

Canine parvovirus (CPV) is a common cause of enteritis, immune suppression and systemic inflammation in young dogs. Endothelial markers, such as intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1), and molecules that upregulate their expression, such as high mobility group box 1 protein (HMGB-1), provide insight into the state of the endothelium during inflammation. This study aimed to determine if circulating concentrations of ICAM-1, VCAM-1 and HMGB-1 were altered in CPV enteritis compared to healthy controls, and whether a correlation existed between these molecules and the degree of inflammation. Thirty dogs with naturally occurring CPV enteritis and ten control dogs were included. Physical examinations, complete blood count and C-reactive protein (CRP) measurements were performed on all dogs at presentation. The concentrations of ICAM-1, VCAM-1 and HMGB-1 were measured using commercially available canine-specific enzyme-linked immunosorbent assay (ELISA) kits. In dogs with CPV enteritis, ICAM-1 concentrations were significantly lower (median: 5.9 [IQR: 4.3-8.3]) and CRP higher (134 [IQR: 85-195]) compared to controls (8.0 [IQR: 6.9-10.3], p = 0.008; 1 [IQR: 0-7], p < 0.001). No significant difference was found for VCAM- 1 and HMGB-1. A strong correlation was identified between VCAM-1 and segmented neutrophil count (r = 0.612, p < 0.001). Despite the presence of systemic inflammation in CPV enteritis, evidenced by high CRP concentrations, our results suggest circulating concentrations of ICAM-1, VCAM-1 and HMGB-1 failed to show an increase. Endothelial activation with subsequent leukocyte adhesion and transmigration through the endothelium may be affected in CPV enteritis and these findings require further investigation.