Subgingival Microbial Ecology and Host Factors Associated with Periodontal Disease in Canines in an Analytical Observational Study

Canine periodontal disease (PD) is a highly prevalent, multifactorial pathology characterized by the complex interaction between the oral microbiota and host factors. The objective of this study was to characterize subgingival microbial isolates and evaluate the association between clinical and biological variables with severe dysbiosis in canines. A cross-sectional, analytical, observational study was conducted on 100 patients treated at veterinary clinics in the city of Loja, Ecuador. Subgingival samples were collected under standardized conditions and processed according to ISO 11133:2014, allowing for the recovery of aerobic, facultative anaerobic, and strictly anaerobic microbiota, with an average of 4.2 bacterial isolates per individual. Statistical analysis included chi-square tests and multivariate logistic regression to estimate odds ratios (OR) and 95% confidence intervals. No statistically significant associations were identified between severe dysbiosis and diet type (mixed diet: OR = 0.91; 95% CI: 0.37–2.25; balanced diet: OR = 1.07; 95% CI: 0.48–2.40), gingivitis severity (OR = 0.97; 95% CI: 0.67–1.40), or cranial morphology (dolichocephalic: OR = 1.08; 95% CI: 0.38–3.15; mesocephalic: OR = 1.07; 95% CI: 0.33–3.57). However, residual analysis revealed discrepancies between observed and expected frequencies, suggesting non-uniform patterns in the distribution of isolates. These findings confirm the polymicrobial nature of the periodontal niche and suggest that the clinical variables evaluated have limited predictive capacity in isolation.