Changes in Immunoglobulins G and A in the Saliva and Serum of Horses with Equine Gastric Ulcer Syndrome (EGUS) and Their Relationship with Other Immune and Redox Status Biomarkers

Equine Gastric Ulcer Syndrome (EGUS) is a widespread disease. It shows variable clinical signs, such as behavioural changes, weight loss, and a reduced appetite, but it has a lack of obvious external symptoms and requires endoscopy for diagnosis. Saliva is gaining attention as a source of biomarkers for EGUS because it can show changes in its composition in response to this disease, and it is also easy and non-stressful to collect. Immunoglobulins (Igs) are important for detecting immune system dysfunctions. In this study, high concentrations of IgA in saliva were detected in horses with EGUS compared to healthy ones, and these changes correlated with other biomarkers from the immune system, such as adenosine deaminase. This would be in line with the results reported in humans, where IgA plays a role in mucosal protection and is elevated in gastric ulcers. These results indicate an involvement of the immune system in the development of EGUS in horses and open up the potential to use IgA as a possible biomarker of this disease.