1Facultad de Ciencias Veterinarias - UNNE. Sgto. Cabral 2139 (3400) Corrientes, Argentina e-mail: llozina@vet.unne.edu.ar

2 Facultad de Ciencias Químicas. UNC, Córdoba, Argentina

Argentine propolis from Mendoza was extracted by maceration using ethanol/water mixtures in different concentrations. The obtained extracts were analyzed by chromatographic methods. Several microbiological methods were used to evaluate which of them can properly determine the antimicrobial activity of the propolis extracts against microorganisms isolated from exudates obtained from the external auditory canal of dogs with otitis. Serial Dilution in Tubes yielded the most consistent results. The results of the Agar Plate Diffusion were directly proportional to the hydrosolubility of the extracts. Therefore, this method did not correctly determine the activity of propolis. Bioauthobiographic assays are suitable alternatives to evaluate the antimicrobial activity of a complex mixture containing many antimicrobial components of varying polarity such as propolis. It should be highlighted the importance of using the correct combination of microbiological methods and chromatographic analysis to determine the compounds responsible for biological activity of propolis. This natural product could be used as a topical antimicrobial in canine otitis.