Gastric ulcers are lesions on the inside of the horse stomach wall, often where gastric acid has eroded the epithelial lining, resulting in ulcer formation. Ulcers occur mainly in the upper non-glandular, and therefore unprotected, area of the stomach, especially around the Margo plicatus (the area between the upper and lower stomach) and the exit to the duodenum, but they also occur in the lower glandular region. Vets use a grading system from 1-4 to describe the severity of ulcers, with 1 being the least severe and 4 the most.How are ulcers diagnosed?They are best diagnosed by a vet using an endoscope, which is a long tube with a camera on the end which is passed through the nose gently down to the stomach.What are the symptoms?The symptoms of gastric ulcers can be vague which is why it is so helpful to use an endoscope to see whether they are present and how severe they are. A horse may go off his feed and generally look unthrifty with a poor coat. Colic may occur when severe ulceration is present. A grumpy attitude and various types of stereotypical behaviour, notably crib-biting and/or windsucking and poor performance are often noted. More specific symptoms include ‘grunting’ when girthed-up or stretching out over a jump; and teeth grinding.For help and advice on feeding horses with gastric ulcers call our multiple-award-winning helpline on 01845 565 030.