Morphological remodeling of canine lymphocytes in Ehrlichia canis infection: quantitative analysis by scanning...

This study aimed to quantitatively assess morphological surface changes in lymphocytes from dogs naturally infected withEhrlichia canisusing scanning electron microscopy (SEM), fractal dimension analysis, and nucleus-to-cytoplasm (NC) ratio determination. Thirty dogs (infected group, n=15; control group, n=15) underwent blood count, blood smear analysis, rapid diagnostic testing, and polymerase chain reaction confirmation. Mononuclear cells were isolated by density gradient centrifugation and processed for imaging. Images were analyzed for morphometric measurements and pseudocoloring. The infected group exhibited higher proportions of lymphocytes with medium (44.4%) and low (13.3%) NC ratios compared to controls (22.2% and 8.9%, respectively), indicating cellular activation (p = 0.03). SEM revealed marked reduction in surface protrusions in infected lymphocytes. Morphometric analysis showed no differences in cell length, width, diameter, or circumference area between infected and control group; however, lymphocytes of the infected group displayed greater radius and circumference length (p < 0.05). Fractal dimension values showed no differences between groups (p > 0.05). The integrated approach combining SEM, morphometry, and fractal analysis quantified lymphocyte morphological alterations associated with E. canis infection, reflecting cellular activation and maturation. These findings advance understanding of immunopathological mechanisms in canine ehrlichiosis and highlight the potential of advanced morphometric techniques in immunopathology.