The objective of the study was to determine the frequency of bacterial otitis cases in dogs, the bacteria involved in the infection and the bacterial susceptibility to antibiotics in samples processed during 2001-2006 in a bacteriology laboratory specialized in the veterinary field. A total of 429 laboratory records were used. The most frequent isolated bacteria was Staphylococcus intermedius (27.7%), but other important species were also found (Pseudomonas aeruginosa, Streptococcus sp. and Staphylococcus sp). Ear infections were mostly due to a single bacteria species (63.6%). In susceptibility test using the Kirby-Bauer method the quinolones, aminoglycosides, cephalosporins, and penicillins combined with inhibitors of betalactamics showed better antimicrobial effect, while bacteria species showed high resistance to penicillin, sulpha, tetracyclines, macrolides and lincosamides.