Heads up – I’m not a vet nor a nutritional expert. I am, however, a horse owner with a problem and like most crazy-horse-owners-with-a-problem I’ve extensively Googled it and joined all the Facebook groups! Here’s a summary of my findings (maybe it’ll save you a bit of time!):

Ulcers and Causes

Ulcers can occur in two parts of a horse – the stomach and/or the hind gut. A horse with stomach ulcers are said to have equine squamous gastric disease (ESGD) and/or equine glandular gastric disease (EGGD), depending on where in the stomach the ulcers are present. EGSD describes ulcers in the upper part of the stomach and EGGD the lower.  It’s quite common for horses to have both the stomach and the hindgut.

Stomach ulcers and hind gut ulcers are caused by stomach acid burning the sensitive linings, causing lesions known as ulcers.

Horses continually produce stomach acid. They have evolved to be grazing for up to 18 hours a day and this food, together with the saliva, passing through the digestive system protects the linings.

If for any reason, the acid comes into contact with the linings and burns it, like acid burns the skin.

Often, this is because there’s not enough food in the stomach or hind gut, Limited access to forage is the most common reason for insufficient food going through the digestive system.

Likewise if a horse overproduces acid it will come into contact with the linings, irritate it and cause lesions. Common reasons for the overproduction of acid are stress and high sugar foods, such as grain.



Symptoms are varied and include:

  • weightloss
  • reluctance to go forward
  • dull coat
  • colic
  • changes in behaviour – spooky, girthy

Owners are also reporting tight pectoral and leg muscles sometimes indicate ulcers.

Diagnosis and Treatment

Gastroscopy is the only reliable method of diagnosis for stomach ulcers (there currently isn’t a reliable method of testing for hind gut ulcers but some owners are using a pH test – see below).

Typically the horse will be starved for 12 hours ahead of the procedure.  A light sedation is given and a tube with a camera on the end (the gastroscopy) will be passed up the horse’s nostril, down the esophagus and into the stomach and hind gut.

Starving is important to empty the stomach so that the vet can see the linings. Otherwise the food will obscure the vet’s view. A healthy lining will be a consistent colour, while a horse with ulcers with show red patches and, in severe cases, bleeding.

The procedure can be performed at home or at a veterinary clinic.

Ulcers are graded on a scale of 0-4:

0 – stomach lining is intact, and there is no appearance of reddening

1 -stomach lining is intact but there are areas of reddening

2 – stomach has small single or multiple ulcers

3 – stomach has large single or multiple ulcers

4 – stomach has extensive ulcers, often merged to give areas of deep ulceration

Some owners are also testing the pH of their horses poo, particularly when they suspect ulcers in the hind gut.  A more acidic reading is taken to be an indication that the horse has ulcers or another digestive disorder.

Medicinal treatment comes in two forms:

  1. Omeprazole – is a protein pump inhibitor and reduces the amount of acid the stomach produces. This reduction gives the linings time to heal.  There are many brands, probably the most well known in the UK is GastroGuard.
  2. Sucralfate – a sulfate-alumnium compound that binds with the ulcer, creating a physical barrier which protects the lining from further damage.  It is more commonly used for hind gut ulcers.

(I’ve also read about a hormone treatment, misoprostol.  It works in the same way as omeprazole.)


As ulcers occur when stomach acid comes into contact with the linings of the digestive system, most of the management advice aims to ensure there is food and saliva protecting the stomach and hind gut for as much of the time as possible.

Providing plenty of good quality forage is key to the management of a horse with ulcers, whether that’s hay when stabled or grass when turned out. Where a horse is getting hard feed, reduce the level of sugars and grain.  A chaff based feed before exercise will reduce acid splashing on the stomach lining with the movement. Addressing any stressors is also a key aspect of managing a horse with ulcers.

Feed and supplements

Finding a combination of feed stuffs for an ulcer prone horse is complicated.  There is a lot of information out there, some of which conflicts.

The starting point is always a ‘good’ forage.  On top of this there are hard feeds with a chaff as a base, then a balancer and additional supplements. Additional supplements have a variety of actions; some have a consistency like mucous and are thought to protect the linings, some neutralise the stomach acid and others contain the pre- and pro- biotics.

Good’ forage

I.e. hay or grass that is high in protein, low in sugars and starch, has a balance of major and minor nutrients that reflect those required by a horse.

For horses with ulcers, it can be beneficial to have a relatively high calcium content. Calcium counters the acid and is the active ingredient in human digestive remedies like Rennies. (It’s important to take into consideration the magnesium content too, as calcium and magnesium have a relationship where one can inhibit the uptake of the other, I might do a separate post on this.)

If you don’t know whether your forage is ‘good’ it is well worth talking to a company like ForagePlus who can analyse your forage and recommend how to improve it as well as balance your horses diet. (They recently analysed the grazing and hay at my yard – but that’s for another blog post!)

Straw is thought to have a negative impact on horses with ulcers as it’s low in protein and calcium and being hard and rough, it may scratch the digestive system.

Alfafa (also known as lucerne in the UK) is  thought to be a good forage sa it is relatively high in calcium and, in the form of chaff,  a useful base for hard feeds.

Balancers – these support the base and add any vitamins, minerals and energy sources.


There is a tremendous range of supplements on the market. Most contain some or a combination of:

Probiotics – these are the ‘good’ bacteria in the gut, yeast such as saccharomyces cerevisiae.

Prebiotics – these are the foods of the ‘good’ bacteria in the gut, FOS and MOS for instance.

Substances that are slimy – these protect the lining of the stomach and gut, protecting it from being scratched by food passing through and some stomach acid. Linseed oil, pectin and beta glucans are good examples.

Substances that have a neutralising effect on the stomach acid – calcium and magnesium, for example.


Because feed is such a complicated issue, I’ve written a number of blog posts sharing my research and my decision making process:

Useful sources of information:





Facebook group: Horses with ulcers UK