Objective: To evaluate the efficacy of Lactobacillus pentosus WE7, an equine-origin organism with potentially beneficial in vitro properties, as a probiotic for prevention of neonatal diarrhea in foals.
Design: Randomized controlled clinical trial.
Animals: 153 foals.
Procedure: Foals were enrolled at 24 to 48 hours of age and randomly assigned to treatment or control groups. The treatment group received approximately 2 x 10(11) CFU of freeze-dried L. pentosus WE7 orally once daily for 7 days, whereas the control group received a placebo. Clinical monitoring was performed for 14 days.
Results: Probiotic administration was significantly associated with development of signs of depression, anorexia, and colic and the need for veterinary examination and treatment. Probiotic-treated foals also had more days of diarrhea, compared with the control group, although not significantly. In a multivariate model, probiotic administration was significantly associated with development of diarrhea and diarrhea plus additional clinical abnormalities.
Conclusions and clinical relevance: Administration of L. pentosus WE7 did not prevent diarrhea; rather, it was associated with development of diarrhea and, most importantly, development of diarrhea plus additional clinical abnormalities and the need for veterinary intervention. The promising in vitro properties of L. pentosus WE7 were not evident in vivo. Results raise concern about the variety of untested probiotic products that are commercially available. Safety and efficacy testing needs to be performed for all potential equine probiotics.