Gastric Ulcers in Horses: A Common Issue
Gastric ulcers have become a common problem in horses. Nearly every stable has at least one horse with stomach issues. But what is causing this?
To explain why so many horses suffer from gastric ulcers, we first need to look at the anatomy of the horse. Horses have relatively small stomachs. With a capacity of only about 8-15 liters, the stomach can only handle small amounts of food compared to the horse’s body size. Horses are natural grazers, spending most of their day searching for and eating food. In the wild, they consume small amounts continuously.
The Contrast with Feeding in Stables
Unfortunately, in many riding stables, hay is not given enough attention. Horses are often fed only two small portions of hay per day, which is far too little for a constant grazer. Even more problematic than the quantity of hay is the length of feeding intervals. Unlike humans, horses, as continuous feeders, produce stomach acid all the time, regardless of whether they have eaten. This unused stomach acid can lead to ulcers in the part of the stomach that is unprotected from stomach acid.
Why Hay Is So Important!
When horses chew hay, significantly more saliva is produced compared to when they eat concentrate feed. The saliva acts as a buffer against stomach acid. Therefore, if too little hay is eaten or the intervals between meals are too long, it leads to an overproduction of stomach acid, causing severe problems. Make sure your horse always has enough hay available. At the same time, be careful not to let your horse become overweight, as this is also very harmful.
How Can I Recognize Gastric Ulcers in My Horse?
The symptoms of gastric ulcers in horses are very varied. Some examples include:
- Loss of appetite
- Colic
- Girth or saddle issues
- Frequent yawning
- Chewing without food
- Teeth grinding
- Eating sand or dirt
- Riding problems
- Aggressive behavior
However, many horses with gastric ulcers show no obvious signs at all. Be observant and don't dismiss even subtle symptoms. If you suspect your horse has gastric ulcers, don’t hesitate to contact your veterinarian. They can confirm the diagnosis with a gastroscopy.
What Happens During a Gastroscopy?
Since nearly all of the symptoms listed above can have other causes, proper diagnosis is essential. A definitive diagnosis can only be made using a gastroscopy. During a gastroscopy, a long tube with a camera is inserted through the horse's nose into the digestive tract, allowing the veterinarian to examine the stomach lining. To ensure the stomach lining is properly examined, the horse is sedated for the procedure and must be fasted beforehand so that the stomach is empty.
Most gastroscopies are done at veterinary clinics, but there are also mobile practices that can perform gastroscopies on-site with portable equipment.
How Is the Horse's Stomach Structured?
The horse’s stomach consists of two parts: the “upper” glandular-free part and the “lower” glandular part. The entrance to the stomach lies in the glandular-free section, while the exit is in the glandular part. The two sections are separated by a line known as the "Margo plicatus." The glandular part is coated with a thick mucous layer, which protects the stomach lining from the aggressive stomach acid.
Different Types of Gastric Ulcers
Ulcers in the Glandular-Free Part
The glandular-free part of the stomach is unfortunately not well protected from stomach acid and is vulnerable to feeding errors. Long feeding intervals or excessive amounts of concentrated feed can cause an excess of stomach acid, which comes into contact with and damages the sensitive glandular-free mucosa. Medications or toxins can also cause stomach problems.
For a long time, only ulcers in the glandular-free part of the stomach were known. These ulcers are well-researched, and their causes have been demonstrated in several studies. This is mainly because the endoscopes used for gastroscopy were once only about 3 meters long, making it easy to examine the glandular-free part. However, since longer endoscopes (about 3.7 meters) became available, it has been found that ulcers can also occur in the glandular part of the stomach.
Where Do Ulcers in the Glandular Part Come From?
Feeding-Related Causes
The causes of gastric ulcers in the glandular part of the stomach can be varied. One cause of ulcers at the stomach outlet (pylorus) can be improper feeding. Studies, for example, show that feeding alfalfa chaff, at least in weanlings, can worsen gastric health. The reason for this is not yet fully understood, but it is believed that the higher content of salicylic acid in alfalfa or mechanical irritation caused by the chaff might be contributing factors. Further studies are still needed, especially for older horses.
Stress as a Cause
In many horses, stress is suspected to be a contributing factor to gastric problems. Stress triggers can vary greatly between horses, including an unsuitable stable mate, housing and training conditions, temperament, transportation, or pain. Since horses react individually to stress, there is no one-size-fits-all solution for stress-free management. One horse might feel more comfortable in a box, while another may be happiest in an open stable.
What Can Be Done?
When a horse suffers from gastric issues, proper management is crucial. In addition to reviewing the housing conditions (to reduce stress), feeding should also be assessed. Horses with gastric ulcers should ideally be fed a grain-free diet. It’s also important to ensure an adequate supply of roughage. We recommend at least 1.5 kg of hay per 100 kg body weight per day. Feeding intervals should not exceed 4 hours to prevent acid overload.
Additional Help
In addition to medication, supplements can also help buffer stomach acid. For example, feeds containing calcium carbonate and magnesium oxide can be beneficial. Magnesium also promotes relaxation, which is especially useful for nervous or high-strung horses. Ingredients like pectin or sodium alginates can help protect the sensitive stomach lining. These substances form a gel with stomach acid, coating the stomach and supporting the mucosa, enhancing the natural protective barrier.
Since the gut microbiome (the healthy bacteria in the gut) can also be affected by the disease, it’s important to consider gut health. Probiotics can help restore balance in the digestive system.
References:
- Fedtke et al. (2015) Effects of feeding different roughage-based diets on gastric mucosa after weaning in warmblood foals, Pferdeheilkunde 31 (2015) 6, pp. 596-602
- 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.
- Webinar in collaboration with FS animal health: Dr. Monica Venner (2022) Gastric diseases in horses: New insights!