June 24, 2016

Gastric Ulcers explained

Many of you will know of a horse that has suffered with Equine Gastric Ulcer Syndrome (EGUS) or have suspicions that your own horse may have ulcers. Helen Boast from Westover Vets explains that with an improvement in our ability to diagnose EGUS in horses, they may just be more common than perhaps was initially thought.

About the vetshutterstock_84867952

Helen Boast BVetMed CertAVP (EM) MRCVS

Helen graduated from the Royal Veterinary College in 2008 and joined the team at Westover Vets in 2009. She has a particular interest in equine medicine and after a further two years of study she is now amongst only a handful of veterinarians within the UK classed as ‘Advanced Practitioners’ in Equine Medicine.

Firstly, we have to understand the unique anatomy of a horse’s stomach and how it is designed to function before we can appreciate how ulcers develop. The horse’s stomach is split into two distinct areas; these are separated into the upper part of the stomach, the squamous area, and the lower part of the stomach, the glandular part.

Squamous ulcers

Squamous ulcers are normally caused by ‘acid splash’. This is because the squamous (upper) part of the stomach is not designed to be in contact with acid and therefore has no protection from it. In the ‘wild’, horses would naturally eat a largely forage based diet, this regime produces a fibre ball to float on top of the pool of acid and digestive juices and provide protection. In certain management systems, this fibre ball is not adequately formed. The racing industry is a prime example of this: horses are fed a largely concentrate based (high starch) diet leading to minimal protection against the acid pool. Travelling at a fast pace, ie gallop, has also been shown to predispose ulcer development, this is due to the acid pool being disturbed and acid literally splashing the squamous lining of the stomach causing ulceration to develop. In vitro studies have shown that ulcers can develop as quickly as 30 minutes after acid injury.

There is a recent school of thought that some squamous ulcers may occur secondary to the presence of glandular ulcers.

Glandular ulcers

Glandular ulcers are less straightforward. The glandular (lower) portion of the stomach is designed to be bathed in acid and digestive juices all the time. Ulcers develop here when there is a problem with the mucus lining of this region. This mucus lining is designed to protect the vulnerable mucosa and provide a barrier to the stomach acid, when this fails acid comes into contact with the mucosa and ulcers will develop. These ulcers are typically found at the ‘gastric outflow’ where the stomach joins the first portion of the intestine.

Glandular ulcers are more typically thought to be as a result of external stress and often seem to be more associated with behavioural changes such as aggression and poor performance. Glandular ulcers are more commonly found in sports and leisure horses whereas squamous ulcers are more common in Thoroughbred racehorses.


Mild recurrent colic

Poor appetite

Weight loss

Behavioural changes

Pain or resentment of girthing

Poor performance

Coat changes


Risk factors

There are four proven risk factors in the development of Gastric Ulcers in horses, these are:

  • Straw being the only forage available
  • >2g/kg bodyweight starch fed per day
  • Water not being available in a turn out paddock
  • > 6 hours between forage feeds



Avoiding the risk factors mentioned above is imperative in preventing the development of ulcers in your horse. Try to ensure good quality forage is available at all times. Feeding a small chaff feed (1/2 scoop) 10 minutes prior to exercise will also help to reduce the amount of acid splash during exercise. Using a reputable antacid such as Ekygard will help to reduce acid production and also promote healthy glandular mucosa. Also avoiding lots of starchy feed will help to reduce the risk of ulcer development by reducing stomach acidity, as mentioned above, oil is a good substitute for energy and calorie provision.

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