A formerly willing or docile horse who suddenly becomes sullen, nappy, or refuses work may be showing signs of pain from ulcers. A personality change for a performance horse might include an unwillingness to work forward, or even show signs of discomfort when being tacked up. A horse which suddenly becomes "girthy", meaning that when the saddle girth is tightened the horse lays his or her ears back, stamps, or bites, may be a sign that the horse is experiencing pain from EGUS. As eating and grazing are a horse's primary daily activities, a horse which is suddenly uninterested in feed or hay may be exhibiting signs of ulcers. Eating affects the stomach acids which can cause ulcers, and can cause additional pain for a horse. A horse which is not eating or grazing may also be suffering from a bout of colic, so this symptom should be observed carefully as it can be a sign of life-threatening issues for a horse. Recurrent Colic A colic is an instance where the horse's intestinal tract ceases to function properly, either due to a physical blockage or stomach upset. Horses who colic frequently may also be affected by EGUS, as the upset in stomach chemistry can lead to an improperly functioning intestine, causing colic. Colic symptoms include signs of pain, no bowel movements, and kicking or pawing at the stomach area. As a colic can be dangerous and potentially life threatening, it is critical that this symptom is treated promptly. Poor Condition A loss of weight and condition due to disinterest in food and grazing can be a sign of EGUS. A horse with poor condition will often have a rough, dull coat. Their ribs and spine may become more prominent. These symptoms are caused by improper nutrition if a horse with EGUS does not ingest a balanced diet. As a horse becomes more underweight, the more likely the horse is to develop further issues such as infection or colic due to a lowered immune system. Diarrhea or Reduced Stool Another sign of EGUS in horses is changes in the manure pattern. A horse's manure should be produced frequently, in semi-solid clumps. Horses suffering from EGUS may exhibit loose, watery stools or less frequent bowel movements. This is due to irritation in the stomach and intestines caused by EGUS. While these are symptoms of ulcers in horses, they should be treated as serious--a horse who is not producing manure or who is producing watery stools may colic or dehydrate if not treated promptly.
BUt if your worried I would consult with your vet..