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Canine and Equine Gastric Ulcers

Many types of living creatures can suffer from stomach ulcers. Alan and I both suffered from severe GERD, gastroesophageal reflux disease. Among the many, many characteristics we share, we have both had fundoplications to treat our reflux. I recently started treating my dog for gastric ulcers. And I have treated Kadeen in the past for equine gastric ulcers.

This past week, I fell into a pattern that we called “Aunt Minnie’s approach” when I was in Veterinary School. The term applied to a practitioner who approached diagnostics by thinking, “You have these symptoms. My Aunt Minnie had these symptoms, so you must have Aunt Minnie’s disease…” The first guy I worked for out of veterinary school had about six categories of “Aunt Minnie’s Diseases.” He struggled to diagnose anything that didn’t fit into one of those categories… or he just made them fit.

My diagnostic capabilities are rusty, after years of not practicing. Additionally, the only diagnosing I find myself needing to do these days is on my own animals… and that really messes with my brain. And so it was that it took me a couple of days to figure out what was wrong with my German Shepherd, Mica.

Gastric ulcers in dogs

In last week’s post, I postulated that he had Hemorrhagic Gastroenteritis. That was my “Aunt Minnie’s” diagnosis, as I had dealt with that with my previous Border collie, Reilly. Bloody stools equal HGE… After a good night’s sleep from an exhausting 3-day trip, it dawned on me that he had a bleeding gastric ulcer. I was finally able to connect a few dots and realize what was happening.

Mica has an elbow lameness, although radiographic films found no apparent lesions. He’s been taking NSAIDs, although not consistently for a very long period of time. Dog NSAIDs are like Rimadyl, which is similar to Aleve or Advil in humans. NSAIDs can irritate the stomach. Apparently, he took it long enough to create a gastric ulcer. Because he already suffers from Exocrine Pancreatic Insufficiency, he’s kind of a GI mess on a normal day. Therefore, his fluctuating appetite and inconsistent stools were not a red flag for me.

Because his lameness has not resolved, he has quit walking with me. Because of that, I fully expected his already-finicky appetite to decrease… which it did. But not for the reasons I thought.

But better late than never, I guess. He’s now on appropriate medication. He takes sucralfate three times daily to coat his stomach, and Omeprazole once daily to decrease acid production. No more NSAIDs either. He’s already feeling much better.

Besides NSAID administration, liver disease and cancer are the other two main causes of gastrointestinal perforation or damage in dogs. Interestingly enough, a less common but documented cause of ulcers in dogs is extreme activity, such as sled dog racing.

Gastric ulcers in horses

According to this article by UC Davis, gastric ulcers are extremely common in highly active horses.

Gastric, or stomach, ulcers are sores that form on the stomach lining. They are common in horses, with the prevalence estimated between 50 and 90%. They can affect any horse at any age but occur most frequently in horses that perform athletic activities such as racing, endurance, and showing.

by Amy Young
 July 29, 2019

Another article from the American Association of Equine Practitioners states:

Prevalence in unmedicated racehorses in active training is at least 90%, whereas that in non-racing performance disciplines exceeds 60%.

Frank M. Andrews , DVM, DACVIM, Louisiana State University, School of Veterinary Medicine

The horse stomach secretes gastric fluids on a continuous but variable basis all day long. Incredibly, on average horses secrete nearly 10 gallons of gastric fluid every 24 hours. Compare that to humans, who secrete a gallon or less daily. Humans, dogs, and cats secrete gastric juices based on a cephalic (brain) phase (that food looks and smells good, let’s eat!) followed by a gastric phase (food is present in the stomach, acid is secreted) and a less-well-understood intestinal phase.

Anatomy of the equine stomach

Horses don’t require the presence of food in the stomach to stimulate acid production. That is not a surprise, given that horses are designed to graze all day long. Another factor to understand about equine gastric ulcers is the anatomy of the horse stomach.

equine gastric ulcers

The stomach of the horse is composed of two sections. About one-third of the stomach does not secrete acid, and is less protected from the negative effects of gastric acid. Two-thirds of the stomach has glands that secrete acid and digestive enzymes. That portion of the stomach has more built-in protectors to keep the acid from damaging the stomach tissue.

Ulcers occur when there is an imbalance between the protective factors and the damaging factors. Ulcers in the smaller, non-acid-secreting portion of the stomach are similar to GERD syndrome in humans.

What causes equine gastric ulcers?

Given that the horse is designed to graze all day long, it is not hard to understand how periods of fasting (in the face of constant acid secretion) can be a significant cause of gastric ulcers. However, the reason highly active horses are more prone to ulcers might not be what you expect… The most likely thought is that the stress of regular and challenging training is the culprit. There is no question that stress can contribute to the creation of gastric ulcers. But there are other factors at play.

The UC Davis article referenced above states:

Researchers have found that exercise increases gastric acid production and decreases blood flow to the GI tract. In addition, when horses exercise, the acidic fluid in the stomach splashes and exposes the upper, more vulnerable portion of the stomach to an acidic pH.

by Amy Young
 July 29, 2019

The AAEP article referenced above further clarifies the dynamics at play in a performance horse. They theorize that extremely high levels of exercise may delay the time it takes to empty the stomach, thus increasing the time the stomach is exposed to damaging gastric fluid. Additionally, the simple mechanics of exercise and the increased abdominal pressure from a girth or the need to maintain a “frame” for long periods of time can delay gastric emptying and expose the less-protected area of the stomach to excessive acid.


A high percentage of grain in the diet can also contribute to the formation of gastric ulcers. Volatile fatty acids are produced when grain is digested… adding yet more acidity to the stomach. Certain strains of bacteria are known to create ulcers in humans, and there is some possibility that a similar scenario can occur in horses.

I mentioned the impact of stress previously. Stress doesn’t just have to be the physical stress of intensive training. Prolonged environmental stress can contribute to ulcer formation as well, such as hauling or constantly changing herd dynamics.

Some articles state that bot fly larvae often attach to the area of the stomach that separates the glandular portion of the stomach from the non-glandular side. These sources postulate that the lesions created by the bot larvae predispose the host horse to ulcers. However, this article from New Zealand debunks that theory, stating that no correlation has ever been proven.

What are the signs that your horse might have ulcers?

The AAEP article lists the following signs that a horse is suffering from ulcers:

Clinical signs in horses include poor appetite or failure to consume a meal, dullness, attitude changes, poor appetite, decreased performance, reluctance to train, poor body condition, rough hair coat, weight loss, excessive recumbency, and low-grade colic.

Other articles add that girthiness, teeth grinding, and behavioral changes such as aggressiveness or nervousness are also symptoms of ulcers. Studies have not shown a strong correlation between severity of ulcers and severity of symptoms.

Diagnosis of equine gastric ulcers

The diagnosis of this prevalent disease of horses is made by the presence of clinical signs, followed by endoscopic examination. Veterinarians are likely to make a presumptive diagnosis and begin treatment. If treatment does not improve or resolve the clinical signs, endoscopic examination would be indicated. This is the approach I am taking with Mica, my German Shepherd. I will only scope him if his condition does not improve.

Treatment of equine gastric ulcers

The primary method of treating gastric ulcers is inhibiting acid production. This is done using the drug Omeprazole. This is the same drug that I started giving Mica. Omeprazole is a proton-pump inhibitor, which means it inhibits the production of gastric acid. Omeprazole for horses is available as GastroGard or UlcerGard. More on those shortly. Omeprazole is given once daily at least 30 minutes before feeding.

Additionally, some veterinarians prescribe sucralfate as well. Sucralfate is a drug that binds to the lining of the stomach and provides a physical protection and barrier. Sucralfate cannot be given within an hour of food or other medications. Some sources say two hours! This medication is given 2-3 times daily. Since we feed our dogs first thing in the morning, Alan and I have started giving Mica his first dose of sucralfate when one of us gets up in the wee hours of the morning to answer the call of Mother Nature! (We’re old people, you know!) That way, we can feed all the dogs at the usual time.

There are some management changes that can facilitate healing as well. Reduced training time and access to pasture are common recommendations. (Think about the advice a doctor would give a Type A business person whose stress level was off the charts!) Anti-inflammatory drugs like NSAIDs or steroids create or aggravate ulcers, so don’t use those if at all possible. Keep food in front of your horse as much as you can… feed that acid! Alfalfa hay has been shown to have some buffering properties; therefore, it is often recommended to use alfalfa for 50% of the forage needs.

Ulcerguard vs. Gastroguard

UlcerGard and GastroGard are both oral paste formulations of Omeprazole for horses. UlcerGard is available without a prescription. GastroGard requires a prescription. Ironically, both products have the exact same amount of Omeprazole in each oral syringe… 2.28g (grams). So what is the difference between the two? The difference is in the dose.

UlcerGard is used to prevent gastric ulcers. The normal dose for an average-sized horse is 1 mg/kg of body weight. A 1000 pound horse is roughly 400 kg, so 400 mg would be the dose required. That is 1/4 of a tube of UlcerGard. It is recommended that UlcerGard be administered 2-3 days before a stressful event, during the event, and preferably for a few days after the stressful period.

GastroGard is used to treat ulcers that are already present. That product requires a prescription as it is dosed at four times the dose for UlcerGard, or 4mg/kg. One tube of GastroGard will treat a 1250 pound horse (568 kg). Treatment is daily for 30 days, and it may be wise to scope the horse to confirm that the treatment objective has been reached.

What is the cost comparison? Chewy had prescription GastroGard for $38 per tube. WalMart had UlcerGard for $37 per tube if you used autoship.

The important thing is that you treat your horse with the appropriate amount of drug to accomplish the desired endpoint. Remember it like this… GastroGard guards an already distressed gastric system and UlcerGard helps guard against ulcers in an otherwise healthy gastric system.

One final thought on treating with Omeprazole… It is not recommended that you use non-FDA approved products. There are too many variations related to the shelf life, safety, and efficacy of the knock-off products. You don’t know if your horse is truly getting the necessary amount of Omeprazole.

There is no question that it is much cheaper and easier for me to treat Mica for canine gastric ulcers than it was to treat Kadeen for equine gastric ulcers! He gets one sucralfate tablet per day… not 15! And Omeprazole for him is pretty cheap.

One interesting hiccup to treating Mica with an acid-reducing drug is that it reduces the digestion of his food. As I mentioned previously, he already suffers from Exocrine Pancreatic Insufficiency. His pancreas doesn’t secrete the enzymes necessary to digest his food, so I topdress his food with enzymes. By further limiting his ability to utilize nutrients, we are back to seeing large volumes of loose stools… I can’t win! Hopefully, increased enzymes will counteract the loss of stomach acid.

Have you had to treat a horse with ulcers? Here are a couple of other excellent articles:

UlcerGard, GastroGard, and Unapproved Medication

Equine Gastric Ulcer Syndrome

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