Fecal microbiota changes associated with pathogenic and non-pathogenic diarrheas in foals

Diarrhea is a common disease that could threaten the welfare of newborn foals. While there are several forms of foal diarrhea, the etiologies can be considered known pathogenic or non-pathogenic in nature. Moreover, there are likely differences in the composition of microbial populations in the gastrointestinal tracts of foals depending upon the etiology of diarrhea. Our study aims to examine the microbial population in the feces of foals with both pathogenic and non-pathogenic diarrheas to discern differences in their microbial compositions. Foal diarrhea samples tested positive or negative for common equine neonatal diarrhea pathogens by diagnostic polymerase chain reaction (PCR), which allowed for samples to be segregated as pathogenic or non-pathogenic. Pathogenic samples tested positive for combinations of Clostridium perfringens and/or Clostridioides difficile toxins. As a result, significantly higher alpha diversity was seen in the non-pathogenic samples than in pathogenic ones. Sequencing of the V4 domains of bacterial 16 S rRNA genes demonstrated that non-pathogenic samples had more alpha diversity. Furthermore, eight microbial families and eleven genera showed significant differences in their abundances between pathogenic and non-pathogenic diarrhea samples.