Stomach ulcers represent the most common and clinically significant disease in the upper gastrointestinal system of horses. The term EGUS has been used since the 90’s to describe erosive damage of the stomach lining, regardless of their localization. Recent studies have confirmed the significance of further subdividing this disease, depending on the type of gastric mucosa affected, into Equine Squamous Gastric Disease and Equine Glandular Gastric Disease. Although both diseases are diagnosed by gastroscopy, the severity of the lesions is assessed differently and they further differ significantly in the pathogenesis and, consequently, the treatment and management of the diseases. ESGD occurs as a result of continuous action of gastric acid on the cutaneous mucosa, while the glandular mucosa has defense mechanisms against it and the lesions in EGGD are of an inflammatory nature. In both diseases, the clinical signs include: loss of appetite, poor performance, loss of fitness or weight etc. The treatment of ESGD is based on suppressing the action of gastric acid, primarily by using proton pump inhibitors, such as omeprazole. An adapted diet is also considered very effective in the prevention of ESGD and in management of the disease. In EGGD, in addition to proton pump inhibitors, H2 receptor antagonists, as well as sucralfate and synthetic prostaglandins, which reduce inflammation and promote healing of the gastric mucosa, are used. Prevention of this disease is primarily aimed at reducing risk factors, such as the frequency and duration of exercise and other stressors.