Lactic acid bacteria: potentials in canine formulas for puppies.

The use of probiotics and natural nutraceuticals with demonstrated therapeutic effects for companion animals is becoming increasingly popular in the veterinary community. Probiotics are alternative to antibiotics, which produce adverse effects, such as promoting bacterial resistance and altering the intestinal microbial ecology and in turn affecting the animal's health. In this study, the in vitro safety and technological characteristics of previously isolated beneficial canine strains were evaluated for the design of a probiotic formulation for dogs. The screening of inhibitory substances production was performed in 100 isolates by plate diffusion technique. 30 strains were pre-selected to evaluate their in vitro safety and innocuity by phenotypic and genotypic antibiotic resistance and expression of pathogenicity enzymes related to virulence factors. Finally, 10 were selected to assay their tolerance to gastrointestinal conditions and stress situations such as high temperatures and solute concentrations by microplate assays. Compatibility between the selected strains was also determined in order to include them in a probiotic multi-strain formulation for canines. According to the results obtained, some strains showed inhibitory activity against common pathogens, and 38% were able to produce H₂O₂. Antibiotic resistance genes were detected in only one of the selected strains, none evidenced gelatinase or lecithinase activity and most isolates showed alpha and gamma hemolysis. Resistance to gastrointestinal tract and stress conditions was strain dependent. The compatible strains with complementary beneficial characteristics were: Lactobacillus johnsonii 67, Lactiplantibacillus plantarum 74, Ligilactobacillus salivarius 84 and Pediococcus acidilactici 81 and are being included in the design of a probiotic formulas to be evaluated in small dogs.