One of many contributing factors to periodontal disease severity is oral microflora. In this in vitro study, the antimicrobial kill kinetics of a 0.125% v/v medium-chain triglyceride (ML:8) emulsion were compared to chlorhexidine digluconate (0.12% v/v) and a xylitol-containing dental formulation against resistant biofilm forms of 10 canine and feline periodontal pathogens. The ML:8 emulsion showed significant activity against the biofilm forms of the 10 pathogens. The anti-biofilm efficacy was significantly better than xylitol and comparable to chlorhexidine digluconate. At 5 minutes, the ML:8 and chlorhexidine digluconate solutions had >70% kill rates, which were maintained throughout the 24-hour testing period. The test compound also showed a significantly lower toxicity profile compared to chlorhexidine digluconate. There is potential for this ML:8 emulsion formulation to be used long-term as a water additive, although clinical trials will be required to establish in vivo efficacy.