# Compositional Changes and Comparative Analysis of Oral Microbial Community During the Formation of Canine Dental Calculus

## TL;DR

This study examines how the oral microbial community changes during the formation of dental calculus in dogs, identifying potential biomarkers for periodontal disease.

## Contribution

The study provides a detailed comparative analysis of microbial composition and metabolic pathways during canine dental calculus formation.

## Key findings

- Significant differences in oral microbial community composition were found between healthy dogs and those with plaque or calculus.
- Potential biomarkers like Bacteroides pyogenes and Peptostreptococcus canis were identified for calculus formation.
- The ABC transporter pathway was notably reduced in dogs with dental calculus compared to healthy dogs.

## Abstract

Dental calculus, a major contributor to canine periodontal disease, creates an ideal environment for oral bacteria to adhere to and colonize. However, the compositional changes and differences in the oral microbial community during the formation of canine dental calculus remain poorly characterized. Clarifying these microbial changes could enhance early diagnosis and treatment strategies for canine periodontal disease. In our study, we included 30 dogs, which were divided into three groups, and collected oral samples from each individual. We analyzed the bacterial composition of the oral microbiome through full-length 16S ribosomal RNA (rRNA) gene sequencing (V1–V9 regions). Our findings revealed significant differences in oral microbial community composition and predicted metabolic pathways between healthy dogs and those affected by plaque or calculus. Importantly, distinct taxonomic markers were identified at the phylum, genus, and species levels, which may serve as potential biomarkers for calculus formation and even periodontitis. However, the mechanistic roles of these species in calculus development require further investigation.

Periodontal disease remains a prevalent clinical condition in dogs, significantly impacting the quality of life of affected animals. Dental calculus is closely associated with periodontal disease, primarily because it serves as a reservoir for dental plaque and bacterial toxins, that contribute to gingival inflammation. To investigate the changes in the oral microbiome during the formation of dental calculus, a total of 30 dogs were enrolled and divided into three groups: healthy dogs (H, n = 10), provided tooth surface samples; dogs with dental plaque (P, n = 10) supplied plaque samples; and dogs with dental calculus (C, n = 10) provided calculus samples. DNA was subsequently extracted from all collected samples and subjected to PacBio sequencing. The results revealed significant differences in the composition and diversity of the oral microbiome between the plaque and calculus groups compared to the healthy group. As calculus gradually formed, the relative abundance of Pseudomonadota decreased significantly, while the proportions of Bacillota, Actinomycetota, Campylobacterota, and Thermodesulfobacteriota increased markedly. Bacteroides pyogenes and Peptostreptococcus canis were identified as potential biomarkers associated with calculus formation, whereas Conchiformibius steedae and Pasteurellaceae bacterium canine oral taxon 271 may serve as indicators of healthy periodontal tissue. Functional prediction analysis revealed a notable reduction in the ABC transporter pathway in the oral microbiota of dogs with dental calculus compared to the healthy group. In conclusion, our study has revealed the compositional changes in the oral microbial community and potential metabolic pathways during the formation of dental calculus in dogs. These findings provide a theoretical foundation for the identification of potential microbial biomarkers and for developing preventive and therapeutic strategies for canine periodontal disease.