Gastric ulcers in a horse’s stomach are the result of erosion of the stomach lining due to prolonged exposure to the digestive acids the horse’s stomach continuously secretes.

In the wild, when a horse is grazing for up to 16hr a day, the acidity is reduced by the forage and also by bicarbonate in the saliva. If stabled horses regularly have access to hay and grazing, this natural preventative process continues. But if they are fed high-concentrate diets with only limited access to forage, the acidity in the stomach increases.

Any period without forage intake, whether due to management practices or illness, leads to increased gastric acidity and risk of ulcers.

Diagnosing gastric ulcers

As few horses with gastric ulcers show clearly defined outward signs, diagnosis of gastric ulceration is not straight forward. Clues that suggest a performance horse may be suffering from gastric ulcers include:

  • decreased performance
  • attitude change (reluctance to work)
  • poor body condition
  • reduced appetite
  • low-grade colic

Clinical signs in foals, also prone to gastric ulcers, include:

  • intermittent colic
  • diarrhoea
  • poor appetite
  • grinding of teeth (bruxism)
  • excess salivation (ptyalism)

All these signs may lead to a presumptive diagnosis. A definitive diagnosis can only be made by a vet using a video or fibreoptic endoscope to observe the stomach lining in adult horses (gastric endoscopy).

Watch video of gastric endoscopy

Dr Tim Brazil, a European Specialist in equine medicine, adds that there is often a delay in attributing deteriorated performance to gastric ulcers.

“A significant number of horses will only show, at best, vague symptoms that may lead to a diagnosis of ulceration. Indeed, a vet will often only turn to the possibility of gastric ulcers if no other problem or illness manifests itself upon initial clinical examination,” he says.

“Horses that are being subjected to an ever-increasing workload are the most susceptible to ulcers. National hunt horses are the most severely affected. They have a pretty stressful training regime.

“Stress created by training is one of the most likely causes of ulceration, and this can manifest itself in a horse breathing or panting more after exercise and going off its food.”

Another consideration is that the high abdominal pressures that occur in the galloping horse may be sufficient to squeeze the acid stomach contents into the upper, acid-sensitive non-glandular portion of the stomach.

Intensive exercise may have a number of adverse effects on gastric physiology, such as reducing blood flow to the stomach, increasing the acid secretion or delaying emptying of the stomach contents into the small intestine.

Gastric ulcer treatments

“Once diagnosed, ulceration can be treated, and a maintenance medication is often a good idea to prevent a recurrence of the illness,” says Dr Brazil.

Management changes are an essential part of the treatment for horses with gastric ulceration. Affected horses need:

  • plenty of time at pasture
  • continuous access to forage, if stabled
  • minimal stress
  • a reduced level of training
  • reduced levels of grain and concentrates in the diet

Unfortunately, these recommendations are hard to achieve for racehorses and other elite equine athletes, so medication is needed to help heal the ulcers and prevent recurrence. The primary principle is to reduce gastric acidity, either by changing management or medical treatment.

This veterinary feature was first published in Horse & Hound (24 May, ’07)