A network survey on pathogenic aerobic strains from canine pathologies of otitis (44%), urinary (17%), respiratory (9%) and dermatological (30%) infections has been established by Vetoquinol in Europe since 1994. The 1474 isolated strains showed that the main pathogenic strains were Staphylococcus intermedius, Staphylococcus aureus (between 40 and 64%) and Pseudomonas aeruginosa (between 22 and 38%) from otitis and dermatological infections, Bordetella bronchiseptica (39%) and Pasteurella multocida (30%) from respiratory infections, and Escherichia coli (61%) from urinary infections. Activity testing (by antibiograms) of the main anti-infectious drugs against these pathogenic strains has shown that marbofloxacin was generally the most active (82 to 100%), followed by amoxicillin/clavulanic acid (1 to 100%), cefalexin (1 to 99%), doxycycline (1 to 100%) and clindamycin (0 to 84%). The main multiresistant strains (up to hexa-R) were observed for Pseudomonas spp. strains from otitis. Marbofloxacin MICs showed a very high activity against P. multocida strains (MIC₉₀ range: 0.025 to 0.413µg/ml), Staphylococcus spp. (MIC₉₀ range: 0.219 to 0.435µg/ml), E. coli strains (MIC₉₀ range: 0.014 to 8.574µg/ml) and B. bronchiseptica (MIC₉₀ range: 0.375 to 0.456µg/ml) and a lower activity against P. aeruginosa (MIC₉₀ range: 0.478 to 12.126µg/ml). MIC₉₀ variability was primarily due to the low number of strains isolated. The marbofloxacin MIC distributions were unimodal for Staphylococcus spp., B. bronchiseptica and P. aeruginosa strains. For the other strains, the distributions were bimodal. Few resistances to marbofloxacin have been observed and mainly for E. coli strains (5%) and Pseudomonas spp. strains (8%), but no significant increase of marbofloxacin MIC₉₀ has been observed excepted for Staphylococcus spp. isolated from otitis since 1994. Consequently, marbofloxacin appears to be effective against the main canine infections even if a limited spread of resistance was observed.