Equine Gastric Ulcer Syndrome

Equine Gastric Ulcer Syndrome, also commonly referred to as EGUS, is a frustrating condition found in horses. On this site we will attempt to break this condition down into the bare basics, giving you as much information, so that you can effectively treat your horse with as little fuss as possible.

Where practical, we will give our view about EGUS from a totally 3rd party perspective, with no conflict of interest from either manufacturers or veterinary practices. Our contributors to this website have spent numerous years working with horses. in the veterinary industry as well as professionally competing at Olympic level.

What is EGUS?

The term “Equine Gastric Ulcer Syndrome” (EGUS) was first used in 1999 to describe gastric ulceration in horses. As you can see, it is a relatively new term. And because it has “syndrome” attached to it, this means that we do not know exactly what causes it.

Equine Gastric Ulcer Syndrome is an umbrella term for two main disease types:


Equine Gastric Ulcer Syndrome

Equine Gastric Ulcer Syndrome is an umbrella term for two main disease types

As you can see, EGUS can be split into two distinct different types: Equine Squamous Gastric Disease (ESGD) and Equine Glandular Gastric Disease (EGGD). Talk about it being complicated!

What does a horse’s stomach look like?

Before we go any further in determining what type of EGUS your horse is suffering from, let’s have a look at where your horse’s stomach is situated, and what it looks like.

internal view of stomach area in a horse

Internal view of stomach location in a horse

As you can see, despite the size of the horse, the stomach is relatively small in comparison to other internal organs. It’s unbelievable how that small area can cause so many problems.

Here is a video of the internal structure of a horse when in movement.

Now let’s see what the actual stomach looks like in the below picture showing the different areas of the equine stomach:

internal view of an equine stomach

Internal view of an equine stomach

As you can see in the above picture, the equine stomach can be divided into two distinct parts, namely the Squamous, or non-glandular region and and the Glandular region, separated by the Margo Plicatus. Depending on the type of ulcers your horse has developed, this will indicate in what region your horse has the ulcers developing. The top third of a horse’s stomach, the squamous region, is simply an extension of the oesophageal lining.

The bottom two thirds are a regular glandular mucosa.

What breeds of horses are predisposed to getting EGUS?

After a great amount of research into Equine Gastric Ulcer Syndrome, and testing and scoping a massive amount of horses over the years, it has been evident that certain horses are predisposed, or get it more often, than other breeds. In the table below it shows which breeds or more predisposed to getting ulcers than others, and also by type of ulcer as well.

What breeds of horses get ulcers more often? Equine Gastric Ulcer Syndrome

What breeds of horses get ulcers more often?

The table above shows us that horses in more intensive training and activities are more prone to getting Equine Squamous Gastric Disease, while those who are not in training or are used more as leisure horses develop Equine Glandular Gastric Disease. This is a real enigma and a lot of research is being done on this at the moment to find out why.

Broken down into activities in the below table, you have a good idea of horses in training/not in training and how often they develop ulcers.

Horse activities producing Equine Gastric Ulcer Syndrome

Type of activity and how it affects ulcers

EGUS in Foals

Unfortunately foals also get EGUS. With up to 50% of foals getting EGUS, this is another large group of horses to treat. This is a bit of an enigma as well, due to the causes of EGUS in foals. The majority of the cases of equine gastric ulcer syndrome in foals is normally due to the following reason: Foals normally start producing gastric fluids from about two days old, and the pH is normally very high. The unequalness  between mucosal aggressive factors (hydrochloric acid, pepsin, bile acids, organic acids) and mucosal protective factors (mucus, bicarbonate) normally results in equine gastric ulcer syndrome in foals.

Now that we have discussed what causes equine gastric ulcer syndrome (the factors that we DO know about,  let us break it down into their separate diseases and try and make more sense of this complicated disease.

Equine Squamous Gastric Disease (ESGD)

This occurs in the upper third of the equine stomach, where there is no mucous lining to protect it. It is often caused by splash back of gastric juice, which has a high pH level, caused by the horse being exercised. This fits in with the table showing horses with high activities being more prone to developing ESGD. In this simplified picture below, you can see why this splash back affects this region so much.

Simplified diagram of horse's stomach

Simplified diagram of an equine stomach showing Squamous (Non Glandular) and Glandular regions

The non glandular region does not have a protective layer of mucous. I will discuss equine gastric ulcer feeding later, but one of the most important things I can say on that in this section now, is that have a small amount of food in the stomach, essentially a fibre “mat” floating on top of the stomach contents, and this will help a lot in preventing acid splash back.

The acid that splashes up from the glandular region hits the non-protected squamous region, and this causes acid burns and lesions. These lesions form ulcers.

Equine Glandular Gastric Disease

EGGD is a complex disease that is increasingly becoming more studied as people are becoming aware of how little of this disease is actually known. Prevalence appears to be variable, depending upon breed and discipline. Primary identified risk factors include exercise frequency, and stress; therefore, management strategies are focused on reducing exercise and stress. Limiting grain intake and increasing pasture turnout may also be helpful preventative measures.

Common gastric ulcer symptoms in horses

There is only one reliable means to test if your horse has ulcers, and that is with the use of a gastroscope. A gastroscope is a long instrument that has a little motor inside, with a camera as well. The horse is normally sedated and does not know what is happening, and also they do not feel any pain. This camera is lubricated very well, and passed through the nose into the stomach area. The veterinarian will view the inside of the horse’s stomach with the camera, normally attached to a monitor. Veterinarians use a 3m long narrow flexible video gastroscope camera which is passed up the sedated horse’s nose and into their stomach via their oesophagus. This is a relatively simple and painless procedure which is generally well tolerated in a sedated horse. The horse must have been fasted over night prior to the examination to ensure no food material obscures our vision (no food for 12 hours and no water for 4 hours). It is often a good idea to ask your vet if you can stable the horse at their facilities the night before if this is possible.

So to get to the stage of knowing if your horse has gastric ulcers, there are normally a few key pointer symptoms that will indicate the possibility of gastric ulcers in your horse.

Top 13 signs your horse might suffer from Equine Gastric Ulcer Syndrome

The more symptoms you can identify with your horse below, the more likely your horse is suffering from ulcers:

  • Poor performance
  • Poor appetite
  • Poor body condition
  • Poor coat
  • Mild or recurrent colic
  • Dullness and lethargy
  • Behavioural changes
  • Kicking out when eating
  • Resentment of saddle
  • Resentment of girthing
  • Resentment of rugs
  • Resentment of grooming chest and flanks
  • Bucking/Bolting

My horse has Equine Gastric Ulcers – What do I do?

As you have no doubt thought to yourself reading all of the above info, treating EGUS can be a minefield, and many people have so many questions, and want to know more about equine gastric ulcers feeding, equine gastric ulcer symptoms, equine gastric ulcer treatment and many more questions. We will attempt to answer all of them for you. Equine gastric ulcers. Could you find many gastric ulcers in horses symptoms in your horse? It is not an exact science to determine if your horse has science, but the evidence suggests that the more gastric ulcers symptoms you can find in your horse, the more likely it has ulcers.

Further reading

Equine gastric ulcers feeding

Equine gastric ulcer treatment