The primary objective was to compare plasma concentrations of allergy biomarkers (MCT and histamine), inflammation mediators (IL-6,−10, and−18, CXCL8, CCL2, KC, CRP) and hyaluronan (a marker of endothelial glycocalyx shedding) between dogs with evidence of anaphylaxis after suspected insect exposure, dogs with other critical illness, and healthy controls. The gene discussed is CCL2; the disease is anaphylaxis.