Periodontal diseases are the most frequently diagnosed problem in small animal veterinary medicine. Although their exact cause is not fully understood, bacteria play an important role in their development. Pseudomonas aeruginosa is a Gram-negative, rod-shaped, non-spore-forming bacterium. The living environment of this bacterium may be soil and water; however, it can also be found in humans and animals. Antibiotic treatment of periodontitis may be complicated by the carbapenem resistance of some P. aeruginosa strains, if these bacteria are found to be an aetiological agent. The aim of the study was to identify all bacterial strains isolated from dog with periodontitis