Objectives: To determine the usefulness of MiriChekTM Oral Bacter as compared to traditional clinical methods in the periodontal assessment of dogs with and without periodontitis. Methods: In this study, 61 dogs were clinically examined using the MiriChekTM Oral Bacter test kit, and information regarding breed, age (months), sex, weight, presence of disease, and periodontitis stage was recorded. The test used a sample of supragingival plaque from the upper left premolar of the dogs. Results: This study included 30 and 31 dogs with and without periodontitis, respectively. Periodontitis was more common in older dogs than in younger dogs. The average positive and negative sensitivity rates of the MiriChekTM Oral Bacter test kit were 73.3% and 80.7%, respectively, and were both strongly correlated with the severity of periodontitis. Conclusions: The findings of this study encourage the use of new diagnostic assist test kits, such as MiriChekTM Oral Bacter, for appropriately detecting and diagnosing periodontal disease in dogs.