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

## TL;DR

This study found that dogs with skin infections have higher levels of certain inflammatory markers in their blood, but these levels don't return to normal even after the infection appears to heal.

## Contribution

The study is the first to compare procalcitonin, interleukin-8, and defensin-β in dogs with superficial and deep pyoderma, revealing systemic inflammation patterns.

## Key findings

- Dogs with pyoderma had significantly higher serum concentrations of procalcitonin and interleukin-8 compared to healthy dogs.
- Beta-defensin-2 concentrations were significantly lower in dogs with pyoderma.
- Biomarker levels did not normalize after clinical improvement, suggesting persistent systemic inflammation.

## Abstract

This study investigated serum concentrations of three inflammatory biomarkers—procalcitonin (PCT), interleukin-8 (IL-8), and beta-defensin-2 (Defb2)—in dogs with superficial and deep pyoderma and compared them to healthy control dogs. Dogs affected by pyoderma showed significantly higher serum concentrations of PCT and IL-8, while Defb2 concentrations were significantly lower than in healthy controls, indicating a systemic inflammatory response associated with bacterial skin infection. No significant differences in biomarker concentrations were detected between superficial and deep pyoderma. In dogs re-examined after clinical improvement, biomarker levels remained largely unchanged. These findings suggest that clinical resolution of pyoderma does not necessarily coincide with normalization of systemic inflammatory markers.

Background: 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. Materials and Methods: Serum concentrations of PCT, IL-8, and Defb2 were measured using enzyme-linked immunosorbent assays (ELISA) in healthy control dogs (group 1, n = 40), dogs with superficial pyoderma (group 2a, n = 16), and dogs with deep pyoderma (group 3a, n = 7). A subset of dogs with superficial pyoderma (group 2b, n = 12) was re-evaluated after clinical remission. Biomarker concentrations were statistically compared between groups and over time. Results: 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 (p = 0.07). Follow-up examinations after clinical improvement revealed no significant changes in biomarker concentrations. Conclusions: 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.