A large component of immunity is linked to what is going on within the gastrointestinal tract and a large amount of the body’s immune cells reside within the gastrointestinal tract (Vighi et al. 2008). The gut microbiome and the immune system can play an important role in many conditions that affect the gut such as inflammatory bowel disease, colitis and food allergies as well as conditions outside the gut, such as asthma.
A recent study in horses aimed to look at whether Culicoides hypersensitivity (Sweet-Itch) or severe equine asthma resulted in differences in their intestinal microbiota from normal horses (Kaiser-Thom et al. 2020). To do this they collected rectal swab samples from 140 horses and detailed questionnaires from the owners about their horse. For each allergic horse, a healthy horse from the same stable was also sampled as a matched control.
There was no difference between healthy and allergic horses in diversity of the microbiome. However, the researchers did find that environmental factors such as the type of stable, access to pasture and type of feeds all influenced the bacteria in the samples. There was also a strong location effect meaning that the microbiota was more similar within the same as compared between farms within this study.
The authors concluded that “Our observations suggest that hypersensitivity disorders in adult horses are not associated with an alteration of the intestinal microbiota, but environmental and/or location factors strongly influence these bacteria.”
S. Kaiser-Thom, M. Hilty, and V. Gerber (2020) Effects of hypersensitivity disorders and environmental factors on the equine intestinal microbiota. Vet Q. 2020; 40(1): 97–107. Available HERE
G Vighi, F Marcucci, L Sensi, G Di Cara, and F Frati (2008) Allergy and the gastrointestinal system. Clin Exp Immunol. 2008 Sep; 153(Suppl 1): 3–6. Available HERE