# Assessment of Salivary Biomarkers of Gastric Ulcer in Horses from a Clinical Perspective

## TL;DR

This study identifies potential salivary biomarkers for diagnosing equine gastric ulcers, offering a non-invasive alternative to gastroscopy.

## Contribution

The study introduces salivary biomarkers (IL1-F5, CA VI, serotransferrin, albumin) with moderate accuracy for detecting equine gastric ulcers.

## Key findings

- Salivary levels of IL1-F5, CA VI, serotransferrin, and albumin were significantly higher in horses with clinical EGUS.
- These biomarkers showed moderate diagnostic accuracy (AUC ≥ 0.8) for distinguishing between healthy and EGUS-affected horses.
- PIP was not significantly different between groups, while albumin and PIP varied in non-clinical EGUS cases.

## Abstract

This study aimed to properly quantify five markers (IL1-F5, PIP, CA VI, serotransferrin, and albumin) in horse saliva and assess their possible changes in Equine Gastric Ulcer Syndrome (EGUS) under different clinical conditions. EGUS is highly prevalent in horses, and so far, it’s only reliable antemortem diagnosis is gastroscopy. Validated immunoassays were used to measure these analytes in No EGUS horses and horses with EGUS (separated in two: those with obvious clinical signs and those with no apparent clinical signs). All horses were confirmed by gastroscopy. The five parameters could be measured with high precision and accuracy. The results showed significantly lower levels of IL1-F5, CA VI, serotransferrin, and albumin in the No EGUS horses than in EGUS clinical horses. These same markers showed moderate accuracy (AUC ≥ 0.8) to differentiate between the two health conditions. These findings suggest biomarkers for EGUS, shedding light on alternative, non-invasive ways of screening that would focus the diagnosis and even monitoring.

This study arises from the search for non-invasive diagnostic alternatives for equine gastric ulceration (EGUS), which is prevalent, clinically variable and only confirmed by gastroscopy. The aim is to quantify five salivary biomarkers (IL1-F5, PIP, CA VI, serotransferrin, albumin) under clinical conditions by validated assays and analyse their diagnostic value. Horses were grouped in No EGUS (neither clinical signs of EGUS nor gastric lesions), EGUS non-clinical (apparently no clinical signs of EGUS but with gastric lesions), and EGUS clinical (obvious clinical signs of EGUS and with gastric lesions). The concentration of 5 analytes could be quantified using sandwich ELISA assays, with high precision (CV: 6.79–12.38%) and accuracy (>95%). Mean salivary levels of IL1-F5, CA-VI, serotransferrin and albumin were significantly higher in EGUS clinical horses compared to No EGUS horses, whereas PIP showed no statistical significance. EGUS non-clinical horses showed statistical differences with No EGUS horses for PIP and albumin. In addition, IL1-F5, CA-VI, serotransferrin and albumin showed moderate accuracy to distinguish between No EGUS and EGUS clinical horses (AUC ≥ 0.8), with sensitivity and specificity greater than 77% and 65%, respectively. Therefore, these biomarkers could be a promising starting point for screening horse that might have EGUS in practice.