The term Equine Gastric Ulcer Syndrome (EGUS) has been used since 1999. As there are important differences, the terms Equine Squamous Gastric Disease (ESGD) and Equine Glandular Gastric Disease (EGGD) were introduced in 2015. Risk factors like dietary management, training regimens and drug side effects, as described for NSAIDs, predispose horses to ESGD or EGGD. To date, gastroscopy remains the gold standard for a reliable diagnosis. However, there are new diagnostic approaches using less invasive biomarkers. Based upon current best evidence, the proton pump inhibitor omeprazole is the treatment of choice for both ESGD and EGGD. Alternative nonpharmacological treatments have been investigated due to the high cost of approved omeprazole, long-term adverse effects in humans and the restriction on omeprazole use in some equestrian sports. An update on diagnosis, nonpharmacological treatment options and prevention of ESGD/EGGD is the focus of this review.