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August 10, 2010

Mobile Horses Part 7: Ulcers

These ulcers are all in the upper, or squamous mucosa, part of the stomach lining. The lesions increase in severity from left to right. Photo by Harold C. McKenzie III, DVM, Virginia Tech’s Marion duPont Scott Equine Medical Center

Check back every Wednesday through Aug. 18 for more articles in the Mobile Horses: Care On The Road series, sponsored by UlcerGard.You can find all the articles on our Mobile Horses page.

 The negative effects of stress are a recurring theme when discussing how to care for horses that spend a great deal of time traveling from show to show, and one of the most common indications of stress is ulcers. Even though the physiological responses to stress are a natural reaction, we create a great deal of unnatural stress in our horses’ lives by making them adapt to our lifestyle.

One of the easiest ways to prevent stress-induced health problems, such as ulcers, is to keep horses in the most natural environment possible. But it’s not always feasible to keep performance horses turned out in a large grass field 24 hours a day, so horse owners need to take additional steps to maintain the health of the stabled horse that spends a lot of time on the road.

A Quick Lesson In Equine Digestion

Equine Gastric Ulcer Syndrome has become highly prevalent in horses—an estimated 93 percent of racehorses and 63 percent of non-racing performance horses develop ulcers during their careers. Unlike human ulcers, which are associated with the Helicobacter pylori bacterium, EGUS has no correlation with the bacterium, and it has never been found in horses. If ulcers in horses aren’t caused by bacteria, then how do they get there?

Horses are herbivores, therefore the anatomy and operation of their digestive system is very different from a human’s. They have a very small stomach (about four gallons at max capacity) which functions best with small, frequent meals, just as a horse would eat in the wild.

“It has been demonstrated that feeding frequency has an important impact on gastric ulceration,” said Richard Wheeler, DVM, of Palm Beach Equine Medical Centers. “A protocol of repeated 24-hour periods of fasting and feeding has been shown to induce erosion and ulceration of the stomach lining. These findings are attributed to exposure of the stomach lining to acid, which is secreted continuously in the horse and specifically secreted following meal feeding. I recommend a ‘little and often’ program for feeding horses with regard to both grain and roughage. Increasing the frequency of feeding has also been shown to assist with digestion and absorption.”

Because a horse is designed to eat constantly, a horse’s stomach continuously produces hydrochloric acid and pepsin, which are digestive enzymes. The horse’s stomach is also made of two parts, the glandular epithelium and the squamous epithelium. The glandular epithelium contains many glands that produce the digestive enzymes, while the squamous epithelium doesn’t contain any glands and serves as a place to contain food. The glandular epithelium also produces factors that help protect the stomach, such as the mucus-bicarbonate layer, which prevents acid from physically contacting the stomach, and prostaglandin E, which helps increase blood flow in the stomach lining.

When a horse eats continuously, the stomach is constantly working to break down food and move it through the digestive tract, which creates a healthy digestive environment. When horses are fed large meals infrequently, like many typical feeding programs, their stomachs empty more quickly and leave the stomach with nothing to do. The stomach continues to secrete gastric acids, and the stomach environment becomes more and more acidic.

EGUS is considered a “man-made” disease because of the way we have forced our horses to change their natural grazing instincts and disrupted the natural digestive process.

An Ulcer Is Born

Now that the stomach is primed and ready for ulcer development, it doesn’t take much for an ulcer to begin to form. An ulcer is defined as an “erosion, or sloughing of one or multiple areas of the surface layers of the stomach.”

“It is thought that some grains high in fermentable carbohydrates can potentially be ulcerogenic while feeds high in calcium and protein can potentially protect the stomach from acid,” said Wheeler. “For this reason, alfalfa hay is thought to be useful in the prevention of gastric ulcers.”

Contributing Factors For Ulcers

  • Infrequent, low-roughage/high-concentrate feeding
  • Infrequent turnout
  • Intensive training
  • Increased stress levels
  • Overuse of non-steroidal anti-inflammatory drugs. (NSAIDs interrupt the production of prostaglandins, which decreases blood flow to the stomach.)

But ulcers are not just reserved for high performance horses. The University of Delaware conducted a study a few years ago that proved EGUS is a real concern for horses in all disciplines.

The study concluded: “Horses transported in a trailer for as little as four hours, and placed in a minimal training program which included being saddled twice daily and trained on a lunge line for three days had significantly higher incidence of gastric changes.”

In the study, 15 horses were put into the program, and 11 of those horses developed EGUS after only one week.

Since our horses cannot tell us that their stomachs hurt, it’s easy for horse owners to miss signs of ulcers, especially when they are on the road and their horse’s behavior may have already changed due to the added stress of travel.

Symptoms Of Ulcers

  • Attitude change
  • Poor appetite
  • Colic
  • Decreased performance
  • Decline in body condition
  • Poor coat
  • Weight loss
  • Dull or uninterested

Unfortunately, the only way to truly diagnose an ulcer is by using an endoscope to see inside the horse’s stomach. The process itself doesn’t take very long (about 15-20 minutes), but requires that the horse’s stomach be empty. The stomach is pumped with air, examined, and then the air is removed.

We’ve Got Ulcers … Now What?

The first step in healing an ulcer is to remove the factors that created it. Horses with ulcers should be allowed as much turnout as possible and should be offered free choice hay if turnout isn’t an option.

There are also several different drug options that can help your horse recover, but it’s essential to know that ulcers won’t heal without several weeks of drug therapy AND changes in their routine.

“Once a diagnosis has been made, I evaluate the horse’s feeding and exercise regime and medical/treatment history. Changes are made with the aim of reducing the risk factors for gastric ulceration that the horse may be exposed to,” said Wheeler. “My treatment regime depends on the specific patient but almost always involves use of a proton pump blocker and a product containing both antacids and sucralfate. Again I will always assess the horse’s environment and daily regime and try to educate the client to prevent further expsoure to risk factors.”

Ulcer Drugs Defined

  • Proton Pump Inhibitors (omeprazole)
    • Proton (or hydrogen) pumps produce acid in the cells. Preventing these pumps from working will decrease acid levels in the stomach.
    • Omeprazole is the only product that is FDA-approved specifically for the prevention of ulcers.
    • Normally given once per day. 
  • H-2 Blockers
    • Cimetidine, ranitidine and famotidine are histamine blockers. Histamine stimulates acid production.
    • Normally given three times per day.
  • Sucralfate
    • Blocks acid from contacting the stomach lining. Best for ulcers in the glandular mucosa, while most horses have ulcers in the squamous mucosa.
  • Antacid
    • Mostly used in humans, but some recommend them for horses. However, the effect only works for about an hour, and large quantities must be used to be affective.

Management Is The Key To Prevention

Because ulcers are a man-made disease, it means that we can prevent our horses from developing them by simply understanding the very nature of the horse itself.

  • Allow free choice access to grass or hay.
  • Allow socialization while a horse is stalled. Make his friends visible.
  • Feed more frequently. Ideally, a horse should never go longer than four to six hours without eating.
  • Decrease grains in your horse’s diet, especially high carbohydrate grains like corn.
  • Limit stressful situations as much as possible.
  • Work to make potentially stressful situations easier for your horse through conscientious management.

“Prevention is always better than cure; I try to promote the role of the veterinarian as a source of advice and consultation before problems arise,” said Wheeler. “I recommend at least once yearly that clients spend some time discussing their feeding, training and medication regime with their veterinarian. These discussions will often produce recommendations regarding frequency and type of feeding, exercise regimes and judicial use of medications that are known to promote ulcer formation. We may also recommend the prophylactic use of medications to reduce gastric acidity at specific times.”

 

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