Culturable Opportunistic Bacteria and Antimicrobial Susceptibility Patterns in Canine Periodontal Pockets: A Pilot Study

Canine periodontitis is one of the most prevalent chronic diseases for dogs over two years of age. Periodontal pockets may serve as a reservoir for opportunistic bacteria including Pasteurella stomatis, Neisseria animaloris, and Streptococcus canis; however, data on their antimicrobial susceptibility and potential One Health relevance remain limited. This pilot study investigated culturable bacterial isolates recovered from periodontal pockets of dogs with different stages of periodontal disease. Subgingival samples were collected under general anesthesia after periodontal probing and dental radiographic assessment during routine comprehensive oral health assessment and treatment (COHAT) procedures. Bacterial isolates were cultured, identified using MALDI-TOF MS, and tested for minimum inhibitory concentrations (MIC) against amoxicillin (AML), doxycycline (DX), trimethoprim–sulfamethoxazole (SXT), gentamicin (CN), chloramphenicol (C), and ciprofloxacin (CIP). In total, 122 isolates from 101 dogs were analyzed, including Pasteurella stomatis (n = 54), Neisseria animaloris (n = 33), and Streptococcus canis (n = 35). MIC distributions varied between bacterial species and antimicrobial agents, while interpretation was limited by the lack of species-specific veterinary medicine breakpoints for some isolates. These preliminary findings highlight the need for larger standardized studies to support antimicrobial resistance surveillance in canine oral microbiota.