Clinical periodontal indices are associated with systemic inflammatory and oxidative stress biomarkers in dogs with periodontal disease

Background Periodontal disease is a common chronic inflammatory condition in dogs and may be associated with systemic inflammatory and oxidative alterations. However, the relationship between clinical periodontal severity and circulating inflammatory and redox biomarkers remains insufficiently characterized. Objectives This study aimed to evaluate the associations between periodontal status, clinical periodontal indices, and systemic inflammatory and oxidative stress biomarkers in client-owned dogs. Methods A total of 131 client-owned dogs were enrolled in this cross-sectional observational study, including 70 clinically healthy dogs and 61 dogs with periodontal disease. Periodontal status was assessed using visual evaluation of plaque index (PI) and gingival index (GI). Serum concentrations of interleukin-6 (IL-6), C-reactive protein (CRP), serum amyloid A (SAA), malondialdehyde (MDA), and total antioxidant capacity (TAC) were measured. Group comparisons and correlations between periodontal indices and biomarkers were performed using non-parametric statistical analyses. Results Dogs with periodontal disease showed significantly higher serum concentrations of IL-6, CRP, SAA, and MDA, along with reduced TAC levels, compared with healthy dogs ( p < 0.05). Increasing PI and GI severity categories were associated with progressive alterations in inflammatory and oxidative biomarkers. PI demonstrated very strong positive correlations with CRP, SAA, and IL-6, whereas GI showed significant but comparatively weaker correlations with these inflammatory markers. MDA showed moderate positive associations, while TAC exhibited weak inverse correlations with periodontal indices. After adjustment for demographic confounders, periodontal disease status remained significantly associated with increased IL-6, CRP, SAA, and MDA concentrations and decreased TAC levels. Age showed modest associations with periodontal indices, whereas sex was not significantly related to periodontal severity or biomarker concentrations. Conclusions Canine periodontal disease is associated with coordinated systemic inflammatory activation and oxidative imbalance. The stronger associations observed for inflammatory biomarkers compared with oxidative stress markers suggest that systemic inflammation represents the predominant biological response accompanying disease progression. Integrated evaluation of clinical periodontal parameters and circulating biomarkers may provide additional insight into the biological characteristics of canine periodontal disease, although longitudinal studies are required to determine causal relationships.