NEW PROBIOTICS FOR PETS’ HEALTH: isolation, characterization and in vivo studies on dogs and cats

The microbiota is considered of fundamental importance in the maintenance of gastrointestinal tract health and animals physiology. Major functions of the gut microbiota include protection against pathogens, detoxification of some catabolites introduced with the diet and stimulation of the immune system [1]. Many factors can modify the composition and the metabolic activity of the intestinal microbiota and any disturbance within the gut microbiota may lead to the development of a multitude of diseases and disorders, such as dirrhoea, allergies, obesity and stress symptoms [2]. There are several strategies to improve and maintain balanced the microbiota, such as probiotic supplementation. The probiotic bacterial species should be of canine/feline intestinal origin exhibiting host specificity. The aim of the present study was to isolate and characterize potential probiotic Lactobacillus strains for canine and feline use by screening and identifying specific bacteria from healthy dogs and cats’ faecal samples. Two in vivo pilot studies on dogs and cats were performed to confirm the capacity of selected specific strains to survive and colonize the intestine of animal subjects. From fresh faecal samples, collected from healthy dogs and cats, morphologically different colonies were isolated onto MRS and Rogosa agar and then identified by biochemical and molecular techniques. Isolated bacterial strains have been screened for their probiotic properties including survival to gastric and pancreatic juices, survival to bile salts, resistance to antibiotics, antimicrobial activity [3], adhesion capacity to HT29 cells, plasmidic and RAPD genotyping profiles [4]. Resistance to freeze-drying, production and subsequent in vivo administration of 6x109 cells/die evaluating strain intestinal permanence, were also tested for the selected probiotic strains [2]. Seven out of 12 Lactobacillus strains isolated from dogs’ faeces were tolerant to gastric stress, while from 11 Lactobacillus strains isolated from cats just 4 strains were resistant to gastric passage. All these strains were also resistant to clindamycin and with significant antimicrobial capacity towards some pathogenic strains tested, variable according to the strain. They were identified by morphological and molecular characterization, comparing the 16S rRNA gene sequence with the BLAST database, as L. reuteri, L. johnsonii, L. paracasei, L. fermentum. Adhesion to HT29 epithelial cells have been in vitro verified on L. reuteri AIII, L. paracasei D3C4 and L. fermentum BM10 chosen as the best probiotic candidates for dogs and cats. No loss of vitality has been recorded due to the freeze-drying process of all three probiotic strains selected. For both dogs and cats, the in vivo study was divided into three periods: the baseline (T0), 3 weeks of probiotic supplementation (T3ws) and one-week after the supplementation period (T4ws). Even if they are preliminary results, both L. reuteri AIII and L. fermentum BM10 administered to dogs and cats, respectively, increased the Lactobacillus spp. concentration after 3 weeks of probiotic supplementation. The average value of recovery percentage of probiotic strains tested at the end of the administration period and after one-week of follow-up was significantly higher respect to the total count of Lactobacillus spp., confirming the colonization of the pets’ intestine. Among several selected probiotic strains, L. reuteri AIII, L. paracasei D3C4 and L. fermentum BM10 proved to be the best probiotic candidates to be used as an ingredient in a functional food or dietary supplement for dogs and cats. The current evidence suggests that specific probiotic strains and/or their combinations may be useful in the canine and feline nutrition, therapy and care. The probiotics of human origin appear to be new promising tools for the maintenance of pets’ health, but the host-derived microorganisms might be the most appropriate probiotic source. Control of intestinal pathogenic microorganisms in dogs and cats is a growing concern and the selection of autochthonous probiotic bacterial strains to overcome some of the gut problems associated with the modern domestication of animals is a valuable tool.