Equine Intestinal Microbiome in Hypersensitivity Disorders

Background: Recent evidence suggests that an altered intestinal microbiome, namely a reduction of bacterial diversity or a shift in microbial composition, is associated with the development of hypersensitivity diseases in humans but this is unknown for horses.Hypothesis: We hypothesized that horses affected by either Culicoides hypersensitivity (CH) or severe equine asthma (SEA) or both show a decreased diversity of their intestinal microbiome in comparison to healthy peers.Methods: Rectal swab samples of a total of 140 horses were collected. Horses were divided into three groups. “CH” comprised 30 horses affected by Culicoides hypersensitivity, group “SEA” consisted of 30 horses suffering from severe equine asthma and group “CH-SEA” comprised 10 horses affected by both aforementioned diseases. For each allergic horse a healthy peer from the same stable was similarly sampled as a matched control. Microbiota in the swabs were determined by assessing the V4 region of the bacterial 16S rRNA gene by means of Illumina MiSeq. Structures of bacterial communities were investigated by means of alpha and beta diversity indices.