Screening of the equine intestinal microflora for potential probiotic organisms

REASONS FOR PERFORMING STUDY: Probiotics have not been demonstrated to provide any beneficial health effects in horses, possibly because of improper selection of probiotic organisms. This study was designed to identify lactic acid bacteria of equine origin with predetermined beneficial properties which might make them useful as therapeutic probiotics. HYPOTHESIS: A small percentage of lactic acid bacteria that are native to the intestinal tract of horses possess properties that may be useful in the treatment and/or prevention of gastrointestinal disease in horses. METHODS: Faecal samples were collected from healthy mature horses and foals. Lactic acid bacteria were isolated and tested for the ability to grow in acid and bile environments, aerotolerance and in vitro inhibition of enteropathogens. One isolate that possessed these properties was administered orally to healthy mature horses and foals and gastrointestinal survival was assessed. RESULTS: Of the 47 tested organisms, 18 were deemed to be adequately acid- and bile-tolerant. All were aerotolerant. Four organisms markedly inhibited Salmonella spp. One isolate, Lactobacillus pentosus WE7, was subjectively superior and chosen for further study. It was also inhibitory against E. coli, moderately inhibitory against S. zooepidemicus and C. difficile and mildly inhibitory against C. perfringens. After oral administration, this isolate was recovered from the faeces of 8/9 (89%) foals and 7/8 (87.5%) mature horses. CONCLUSIONS: Lactobacillus pentosus WE7 possesses in vitro and in vivo properties that may be useful for the prevention and treatment of enteric disease in horses. POTENTIAL RELEVANCE: The beneficial in vitro and in vivo properties that L. pentosus WE7 possesses indicate that randomised, blinded, placebo-controlled efficacy studies are warranted.