BackgroundAn important aspect in the microbiology of the reproductive system of small animals is the potential occurrence of probiotic bacteria, such as lactic acid bacteria (LAB) of the genusLactobacillus. The presence of these microorganisms is significant due to their strong antibacterial and antifungal properties. This study aimed to select probiotic strains from the oral cavity and vagina that have outstanding antibacterial properties against typical genital pathogens of the female dog reproductive tract.ResultsThe antagonistic activity of ten LAB strains was tested against seven etiological agents isolated from the genital tract of female dogs with signs of inflammation. LAB strains with the greatest ability to inhibit the growth of indicator bacteria wereLactobacillus plantarumandL. acidophilus, whileL. fermentumandL. brevisstrains inhibited growth the least. Almost all strains showed a complete lack of adherence to Caco-2 epithelial cells.ConclusionsAll tested LAB isolates inhibited the in vitro growth of either Gram-positive or Gram-negative pathogens, suggesting that potential probiotic strains could contribute to the balance of the normal vaginal microbiota. Furthermore, they could be considered for use as prophylactic agents or as an alternative to antibiotic therapy for infections in dogs.