Gastric ulceration is a serious yet common condition that can affect any horse – from the most sedate pony to performance and racehorses.
Studies indicate that gastric ulcers occur in up to:
- 37% of leisure horses1
- 63% of performance horses2,3
- 93% of racehorses4
Foals are also at particular risk - around 50% of foals develop stomach ulcers, particularly in the first few months of life5.
All the risk factors for equine gastric ulcers have yet to be determined, but some of the more commonly encountered ones are presented below. It is important to note, however, that horses can develop severe ulcers even in the absence of these characteristic risk factors1,5.
As horses are ‘trickle feeders’ there is a continuous secretion of acid within the stomach, so prolonged periods without food to neutralise that acid can lead to ulceration. When horses are denied free access to feed or fail to eat, ulcers develop rapidly8. Use of concentrated feeds may also contribute to ulcer risk by reducing the time spent feeding and increasing gastrin levels9.
There is a definite association between equine training and gastric ulceration. Even non-intensive training is associated with a high prevalence of stomach ulcers2. It has been shown that blood flow to the stomach (which helps to remove acid) decreases with exercise6 - while increased pressure in the abdomen during exercise pushes acid up into the sensitive portion of the stomach7.
Physical stress and illness
Gastric ulcers can occur in response to physiological stress. Shock, respiratory disease and traumatic injury may play a role. Equine transportation10 and stable confinement8 are proven risk factors in causing ulcers.
While psychological stress is difficult to evaluate in horses and foals, stressful conditions may adversely influence feed intake, resulting in periods of increased stomach acidity11.
Some long-term medications can produce adverse gastric effects, as they may inhibit production of the substances that help to protect the stomach12.