Histomorphometric evaluation of MMP-9 and CD31 expression during healing under Negative Pressure Wound Therapy in dogs.

INTRODUCTION: The aim of the study was to evaluate the molecular and histological effects of negative pressure wound therapy (NPWT) on vascularisation in clinical cases of open wound treatment in dogs. Open wounds (n=10) were randomly assigned to one of two groups: NPWT treatment (n=5) or foam treatment (polyurethane-foam dressing, n=5). Wounds were matched based on age and underlying cause and analysed with respect to neovascularisation (CD31) and matrix proteinase changes (MMP-9). Histological slides were blinded and analysis was performed using automated histomorphometric software. Values determined at day zero after debridement were used as a reference and wound development at day six was evaluated using linear mixed models. Signalment, pre-treatment time and underlying cause were similar between groups. NPWT resulted in a highly significant increase of vascularisation (p.