Gastric ulcers have become a widespread disease in horses. Almost every stable has a horse with stomach problems. But what causes this?
To explain why so many horses have gastric ulcers, we must first look at the horse's anatomy. Horses have a relatively small stomach. With a capacity of only about 8-15 liters, the stomach is only capable of holding small amounts of feed compared to the horse's body mass. The horse is a continuous grazer – in the wild, horses spend most of the day searching for and consuming food. They continuously consume only small amounts of food.
The opposite of feeding in stables
Unfortunately, in many riding stables, too little attention is paid to roughage. Often, horses only receive small portions of hay twice a day. This is far too little for a continuous grazer like a horse. Far more problematic than the amount of hay are the feeding breaks that occur due to insufficient roughage. Unlike humans, a horse, as a continuous grazer, continuously produces stomach acid, regardless of whether it has eaten or not. This unused stomach acid can lead to gastric ulcers in the upper, unprotected area of the stomach.
This is why roughage is so important!
Chewing roughage produces much more saliva compared to concentrates. Saliva has a kind of "buffering effect" on stomach acid. So, if too little roughage is eaten or the periods between meals are simply too long, an overacidification occurs in the horse's stomach, which can cause major problems. Therefore, make sure that your horse always has enough roughage freely available. However, at the same time, make sure that your horse does not become too fat, as this is also very harmful.
How do I recognize gastric ulcers in my horse?
The symptoms in horses with gastric ulcers are very diverse. Examples include:
- Loss of appetite
- Colic
- Girth or saddle discomfort
- Frequent yawning
- Empty chewing
- Teeth grinding
- Eating sand or dirt
- Riding problems
- Aggressive behavior
Not uncommonly, affected horses show no abnormalities at all... Be attentive and do not take even mild symptoms lightly. If you suspect gastric ulcers, do not hesitate to contact your veterinarian. They can provide certainty with a gastroscopy.
What happens during a gastroscopy?
Since almost all of the mentioned symptoms can also have other causes, a correct diagnosis is essential. A reliable diagnosis can only be made by gastroscopy. During gastroscopy, a long tube with a camera, which reaches into the stomach, is inserted into the horse's digestive tract through the nose. For the gastric mucosa to be adequately examined, the horse is sedated for the examination, and the horses must "fast" beforehand so that the stomach is empty during the examination.
Most gastroscopies are performed in an equine clinic. However, there are also some mobile practices that can perform gastroscopy on-site with a portable device.
How is the stomach structured?
A horse's stomach consists of 2 parts. The "upper" glandular-free part and the "lower" glandular part. The entrance to the stomach is in the glandular-free part, and the exit is in the glandular part. Both parts are separated by a boundary line, the Margo plicatus (see photo). The glandular part is covered by a thick layer of mucus (mucosa). This protects the mucous membrane from aggressive stomach acid.
Different forms of gastric ulcers
Gastric ulcers in the non-glandular part
The non-glandular part of the stomach is unfortunately not well protected from stomach acid and is therefore susceptible to feeding errors. Long feeding breaks or too large quantities of concentrate feed can lead to an excess of stomach acid, and the sensitive non-glandular mucous membrane comes into contact with stomach acid and is attacked. Of course, medication or poisoning can also cause stomach problems.
For some time, only gastric ulcers in the non-glandular part were known. These are already quite well researched, and the causes have been proven by several studies. This is mainly due to the fact that the endoscopes used for gastroscopy used to be only about 3m long. This allowed the non-glandular part of the stomach to be examined very well. However, since longer endoscopes have been available (approx. 3.7m length), it has been found that gastric ulcers can also be found in the glandular part of the stomach.
Where do gastric ulcers in the glandular part of the stomach come from?
Causes in feeding
The causes of gastric ulcers in the glandular part of the stomach can be diverse. One cause of gastric ulcers at the pylorus (stomach exit) can be incorrect feed. Studies show, for example, that feeding chopped alfalfa, at least in weanlings, can worsen gastric health.[1],[2] The exact cause is not yet known. It is suspected to be the higher salicylic acid content in alfalfa or the mechanical irritation caused by the chopped material. However, further investigations are still necessary, especially in older horses.
Stress as a cause
In most horses, stress, among other factors, is suspected as a cause of stomach problems. Here, each horse must be examined closely, as the triggers for stress can be manifold. An unsuitable stable neighbor, as well as housing and/or training conditions, general temperament, transport, or even pain can cause stress and stomach problems in horses.[3] However, since horses are very individual in this regard, there is no universal recipe for stress-free keeping. One horse may feel more comfortable in a stall, while another horse, as an outdoor enthusiast, is happiest in an open stable.
What can be done?
If a horse suffers from gastric diseases, proper management is required. In addition to reviewing housing conditions (keyword: stress reduction), feeding should also be reviewed. Horses with gastric ulcers should ideally be fed grain-free. Furthermore, adequate roughage supply must be ensured. We recommend at least 1.5 kg of hay per 100 kg of target body weight per day. Feeding breaks should not last longer than 4 hours to avoid overacidification.
Small helpers can provide support
In addition to medicinal treatment, complementary feeds that buffer aggressive stomach acid can also help. For example, feeds containing calcium carbonate and magnesium oxide are suitable. Magnesium also ensures more calmness and serenity, which can be particularly useful for nervous and temperamental horses. Furthermore, ingredients such as pectins or sodium alginates can help to protect the sensitive gastric mucosa. In conjunction with stomach acid, a type of gel forms, which protects the stomach lining. The "mucosa" is thus supported, and its natural barrier function is improved.
Since the gut microbiome, i.e., the healthy bacteria in the intestine, can also be affected by the disease, intestinal health should not be neglected. Probiotics can help to restore balance to the intestine.
[1] Fedtke et al. (2015) Effects of feeding different roughage-based diets on gastric mucosa after weaning in warmblood foals, Pferdeheilkunde 31 (2015) 6, S. 596-602
[2] Vondran et al. (2016) Effects of two alfalfa preparations with different particle sizes on the gastric mucosa in weanlings: alfalfa chaff versus alfalfa pellets. BMC Vet Res. 2016 Jun 14;12(1):110.
[3] Webinar in collaboration with FS animal health: Dr. Monica Venner (2022) Gastric diseases in horses: There is much new!
