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The equine digestive tract is always a concern for horse owners – and veterinarians! Colic can be caused by many different things, and one possibility is EGUS – Equine Gastric Ulcer Syndrome. Gastric ulcers are actually quite common in horses. There are a variety of reasons for this, but have no fear! While they are common, they are rarely life-threatening and can be cured with appropriate treatment.

First, let’s start with an anatomy overview. The equine stomach is divided into two sections – the non-glandular (or squamous) section, and the glandular area. The line dividing these areas is known as the “margo plicatus”. Stomach acid is secreted by the glandular area. We typically see ulcers along the margo plicatus on the squamous side of the stomach, but we can also see ulcers throughout the non-glandular and glandular regions. Oh yeah, and just to be clear, gastric ulcers are erosions in the normal lining of the stomach. Pretty simple so far, right?

So, why do horses get ulcers, anyway? Well, horses are designed to be grazers, therefore they are continuously secreting acid into their stomach. This is different from humans who secrete acid in response to a stimulus (such as smell of food or eating a meal). Saliva is alkaline (high in pH), and usually balances the acid (low in pH). The trouble is, horses tend to only salivate when they are eating. As humans, we often put horses on our schedule for feeding – a big meal at breakfast and dinner, and maybe a bit at lunch time, too. We have also moved to feeding them large amounts of grain, in order to get sufficient calories into them in a short period of time. A high grain diet increases acid production, as well. Long term drug administration (such as Bute) can also negatively affect the stomach. Lastly, horses are easily stressed. While high workloads are usually to blame (racehorses can have up to 90% prevalence of ulcers), something as simple as pecking order in a herd can be stressful enough for some horses. So, just because your horse is a pasture potato, that doesn’t mean he can’t develop ulcers.

While not all horses with ulcers will show clinical signs, when they do, the signs tend to be vague. Many times, horses will show intermittent bouts of mild colic. They may look at their sides occasionally. Attitude changes often occur and they can become nippy or unwilling to work. “Girthiness” may be noted – where pressure applied to the girth area causes them to be uncomfortable. Weight loss and poor appetite are also sometimes seen. Since the signs are vague, a full workup is often recommended to rule out other diseases.

The best way to diagnose ulcers is by endoscopy. Endoscopy is performed under standing sedation. A long, flexible camera is passed up the nose and nasal passages, down the esophagus and into the stomach. (Note that horses have to be fasted for this in order to allow for a full exam of the stomach) This gives us a full view of the lining of the stomach. We can then grade the severity of ulcers on a scale from 0 to 3.

Severity of Ulcers (from right to left): Grade 0 (normal, healthy stomach) to Grade 3 (Extensive ulceration)

Once ulcers have been diagnosed, we can then begin treatment. The best (and proven) treatment for gastric ulcers is GastroGard. GastroGard is omeprazole which is specially formulated to be absorbed by the equine GI tract. While there are a lot of products out there claiming to contain omeprazole and cure ulcers, none of them have a protective coating to get through the stomach acid to be properly absorbed – except for GastroGard. Also, if you’re using any type of compounded omeprazole that is purple, you might as well squirt it on the ground. This means the drug has become oxidized and is no longer effective. Here’s a study that compared the efficacy of GastroGard with a compounded omeprazole product. While this sounds like an ad for GastroGard, we believe that if you’re going to use omeprazole, this is the only one that should be used. You can learn more about it at

Since GastroGard is pretty darn expensive, it’s not always a financial option for every horse owner. If that’s the case, we do have other tricks up our sleeves. One alternative drug we can use is Ranitidine. Ranitidine actually works so well to “take the burn out” of gastric ulcers, that we often use it as a first line of treatment in an acute episode of colic caused by gastric ulcers (sometimes in combination with GastroGard). The trouble with Ranitidine is that it doesn’t work quite as well for long term healing of gastric ulcers – so we sometimes have to give it for longer, and recurrences are more likely. It also has to be given three times daily, instead of the once daily dosing of GastroGard. But, given these drawbacks, it can be a fair alternative to GastroGard for a more economical price.

We can also make management changes to help reduce the incidence of gastric ulcers, or to help prevent their recurrence. These changes can include offering free choice hay, reducing grain rations, increasing turnout, or changing herd dynamics as necessary. Studies have shown that offering a flake of alfalfa hay about 30 minutes prior to a grain meal can reduce the incidence of gastric ulcers. Along this same line of thinking, there are several “buffering” gastric supplements available over-the-counter, which can be of some benefit. Please note, if you’re considering adding a gastric supplement to your horse’s regimen, check with your vet first. There are MANY of these types of supplements available, and some are not worth the bucket they are packaged in!

While gastric ulcers are a singular cause of colic, they are probably one of the easier ones to treat. With appropriate diagnostics and treatment protocols, we can quickly get your horse back to normal and back to doing those activities that you both love.