Periodontal disease and dental calculus buildup are common dental problems in dogs, and oral bacteria play an important role in the processing of periodontal disease and forming dental calculus. Therefore, the investigation of cultivable bacteria from the gingiva and calculus would be helpful for understanding the microbial population which shifts from normal to develop periodontal disease and buildup dental calculus, and could also be the reference for prevention and treatment of periodontal disease. The purpose of the study is to investigate and compare the distribution of bacteria in normal, and periodontal-diseased gingivae, with dental calculus of the dogs. After processing and culturing all of the gingival swabs and dental calculi, the cultivable bacteria were identified by morphology, traditional biochemistry methods and Biolog automated system. The bacteria, which could not be identified by the methods mentioned above, were tested by 16S rRNA gene sequencing method. Samples from 18 dogs that had normal gingival tissue, and 20 dogs suffering from periodontal disease with dental calculus buildup were collected. Totally, 75 (including 25 genera and 48 species), 99 (including 33 genera and 56 species), and 83 (including 30 genera and 55 species) bacterial strains were identified from normal gingiva, gingiva of periodontal disease, and dental calculus, respectively. In 70 (93.3%) normal gingival cultivable aerobes, Gram-negative (G-) bacteria are the main isolates in which Pasteurella spp. are the superior bacteria. Streptococcus spp. (10 strains, 33.3%) are the primary strains of Gram-positive (G+) aerobes. Clostridium (3 strains) is the main bacteria of 5 anaerobes from normal gingiva. 79 strains (79.8%) of aerobic bacteria are isolated from periodontal-diseased gingiva, including 45 (57%) G- and 34 (43%) G+ strains, in which Pasturella (21 strains, 46.7%) and Streptococcus (8 strains, 23.5%) are the most common isolates, respectively. Prevotella (7 strains, 70%) and Clostridium (4 strains, 40%) are the representatives of G- (10 strains) and G+ (10 strains) bacteria. The highest ratio of G- (41 strains, 59.4%) and G+ (28 strains, 40.6%) bacteria belongs to Pasturella (10 strains, 24.4%) and Corynebacterium (10 strains, 35.7%), respectively, from 69 aerobic isolates of dental calculus. In anaerobes (14 strains) from calculi, Prevotella (5 strains, 62.5%) of G- bacteria (8 strains) is the main type. The primary anaerobic G+ bacteria (6 strains) of dental calculus are Clostridium (2 strains) and Lactobacillus fructivorans (2 strains). The result of the study has shown that Pasturella is the superior genus of three studied groups in aerobic G- bacteria, and its most cultivable species are P. dagmatis, P. canis/stomatis and P. pneumotropica. Streptococcus is the superior aerobic G+ genus in the studied samples, except in the dental calculus, in which Corynebacterium is predominated. In addition, from the result of the ratio of the isolated species, the anaerobes in the gingiva and dental calculus of the periodontal-diseased dogs are increased significantly. Therefore, the shifts of oral bacterial populations and the increased ratio of anaerobes in dogs are worth for the further study on the pathogenesis of periodontal disease and dental calculus buildup.