Investigations of Procalcitonin, Interleukin-8 and Defensin-β in Dogs with Superficial and Deep Pyoderma

<b>Background:</b> Canine pyoderma is a common bacterial skin disease that can be classified as superficial or deep and is associated with inflammatory processes. Systemic inflammatory biomarkers such as procalcitonin (PCT), interleukin-8 (IL-8), and beta-defensin-2 (Defb2) may reflect immune activation; however, their diagnostic and clinical relevance in canine pyoderma remains unclear. <b>Materials and Methods:</b> Serum concentrations of PCT, IL-8, and Defb2 were measured using enzyme-linked immunosorbent assays (ELISA) in healthy control dogs (group 1, <i>n</i> = 40), dogs with superficial pyoderma (group 2a, <i>n</i> = 16), and dogs with deep pyoderma (group 3a, <i>n</i> = 7). A subset of dogs with superficial pyoderma (group 2b, <i>n</i> = 12) was re-evaluated after clinical remission. Biomarker concentrations were statistically compared between groups and over time. <b>Results:</b> Dogs with superficial and deep pyoderma exhibited significantly higher serum concentrations of PCT and IL-8 compared to healthy controls, whereas Defb2 concentrations were significantly reduced in both disease groups. No statistically significant differences were detected between superficial and deep pyoderma for any of the biomarkers, although IL-8 showed a trend toward higher concentrations in dogs with deep pyoderma (<i>p</i> = 0.07). Follow-up examinations after clinical improvement revealed no significant changes in biomarker concentrations. <b>Conclusions:</b> Canine pyoderma is associated with measurable systemic inflammatory alterations, characterized by increased serum concentrations of PCT and IL-8 and decreased Defb2 levels, irrespective of disease depth. The lack of biomarker normalization following clinical remission suggests that systemic inflammatory responses may persist beyond visible clinical healing. While these biomarkers may provide complementary information on inflammatory activity, their utility for monitoring treatment response appears limited.