Equine 74 Blog

Understanding Stomach Ulcers in Horses: Grades 1-4 Explained

Written by Tanja Dietz | 21. Jan 2024

Disclaimer: The following text has been translated from German. It is important to note that if you have any inquiries regarding the feeding of your horse, it is always recommended to consult your veterinarian first.

Stomach ulcers - they are one of the most common diseases in horses today. They usually come unnoticed (to us) and are only treated when they have already caused massive damage to the horse's stomach lining. It should be mentioned here that a stomach ulcer is not just there, but develops over time.

How do stomach ulcers develop?

Stomach ulcers are the (long-term) consequence of over-acidity of the stomach. This can have different causes. The main causes of stomach ulcers are feeding errors and stress. Stress, in turn, can be caused by various factors. These include, among other things, husbandry as well as training. But long-term medication can also be the cause of gastric ulcers. Before the horse develops a gastric ulcer, the mucous membrane is initially irritated.
 
The normally superficially smooth mucosa lining the stomach shows hyperkeratotic changes. This means that the surface is keratinised. According to the so-called "Ulcer Score", this change of the stomach mucosa is called gastric ulcer grade 1. Many horses often show no clear symptoms or even no symptoms at all with such a change in the mucous membrane, so that gastric ulcers often develop undetected. 

Ulcer Score assesses severity of gastric ulcers

 

The Ulcer Score divides stomach ulcers into four different degrees of severity. If the mucous membrane is damaged in one or more small areas, this is called grade 2. Here, gastric ulcers are more frequently recognised. Of course, this also depends on the horse, as every horse expresses pain differently and has a different pain tolerance limit. For example, there are horses that only have an irritated stomach lining and clearly express this through stomach ulcer-typical symptoms, while other horses with severe stomach ulcers hardly show any symptoms and may suffer silently.


If the damage is large, single or in several places, or even extensive on the surface, it is called grade 3 peptic ulcer. If the damage is spread over a large part of the mucosa and has penetrated deep into the mucosa or is even bloody, this condition is rated as grade 4. These mucosal changes are highly painful for horses and are usually hardly accompanied by no symptoms. 

Different symptoms often lead to late diagnosis

 

Because the symptoms that horses express with stomach ulcers are so varied and diverse, a clear diagnosis often takes a long time and horse owners have gone through a multitude of examinations and high veterinary bills before a clear diagnosis of stomach ulcers is made.

For many horse owners, the stomach is not the main cause of a variety of symptoms, such as inability to ride, weight loss, poor feed intake, teeth grinding, altered drinking behavior or coupling, and often, for example, an ill-fitting saddle, the wrong bit, worm infestation or poor feed quality are suspected as the cause of certain symptoms, the "stomach problem" is given free rein and mild irritations of the stomach lining may develop into severe, bloody stomach ulcers, which can only be clearly diagnosed by a gastroscopy of the stomach. 

Many horse owners shy away from a gastroscopy

 
Due to the associated costs and the fact that horses must be fasting for 12-18 hours before the gastroscopy and are not allowed to drink anything for 2 hours before so that food particles do not interfere with the vet's view during the gastroscopy, many people find it difficult to decide to have a gastroscopy performed.
 
However, since a treatment of gastric ulcers on suspicion causes unnecessary costs and a treatment with omeprazole does not pass the horse or the intestinal tract of the horse without leaving a trace, there should be certainty before the treatment. Therefore, a gastroscopy is almost unavoidable, especially as it is easier to assess and estimate the severity of the ulcers and thus the duration of treatment. The more severe the gastric ulcers, the longer it takes for the gastric mucosa to heal completely.