Gastric Ulcers and Your Horse
What are gastric ulcers?
Gastric ulcer syndrome, a very common disease in horses (up to 60-90% of horses in some studies) is an erosion of the stomach mucosa. There are two sections of the horse’s stomach; the glandular portion, which secretes acid and enzymes to break down food, and the stratified squamous portion. These two parts are separated by a barrier called the margo plicatus. A diagram of the inside lining of the horse’s stomach is shown below:
Gastric Ulcers and Your Horse
What are gastric ulcers?
Gastric ulcer syndrome, a very common disease in horses (up to 60-90% of horses in some studies) is an erosion of the stomach mucosa. There are two sections of the horse’s stomach; the glandular portion, which secretes acid and enzymes to break down food, and the stratified squamous portion. These two parts are separated by a barrier called the margo plicatus. A diagram of the inside lining of the horse’s stomach is shown below:
Though gastric ulcers can affect any part of the stomach, generally gastric ulcers affect the squamous part of the stomach and are concentrated around the margo plicatus.
What causes gastric ulcers?
Horses evolved as consistently grazing animals, with access to feed at all times. Therefore, the stomach developed to produce acid and enzymes at all times to aid in digestion. However, as horses were domesticated and were kept in stalls without free access to feed, the consistent acid production was no longer buffered by constant forage intake, eventually causing ulceration of the stomach.
As the stomach is a very acidic environment, the lining of the stomach has developed a series of protective mechanisms to prevent erosion of the lining, including a mucus layer and good mucosal blood flow. By providing these protective mechanisms, the stomach is able produce and utilize gastric acid and enzymes to aid in digestion without causing damage to the stomach lining. However, for various reasons, the acid and enzyme production in the stomach can overwhelm the protective mechanisms, and cause ulcers.
What are the symptoms of gastric ulcers?
Adult horses that suffer from gastric ulcers tend show signs of mild colic, including pawing, flank biting, and flank watching. They will also show more subtle signs such as teeth grinding and can have loose manure. Some owners will note a change in behavior, poor performance, inappetance, weight loss and resistance to girth tightening as well.
How are gastric ulcers diagnosed?
The only way to definitively diagnose gastric ulceration is via gastroscopy. Gastroscopy is performed by passing a small camera through the nostril and nasal passages, past the pharynx, into the esophagus and finally into the stomach. Horses generally must be fasted for at least 12 hours prior to gastroscopy for the stomach to be empty enough to visualize the majority of the stomach lining. As gastroscopy is sometimes expensive or unavailable, many horses are treated empirically based on clinical signs, and assumed to have ulcers if the signs improve with treatment.
How are gastric ulcers treated?
There are numerous supplements and medications to treat gastric ulcers, but the three primary medications used at Woodside Equine Clinic include:
- Omeprazole
o Omeprazole (Gastrogard/Ulcergard) is the only FDA approved medication for the treatment of gastric ulcers in horses. It is a proton pump inhibitor, which means that it works by decreasing the amount of acid that is produced in the stomach. It can be used both for treatment and prevention of gastric ulcers. This medication is usually given once per day orally.
- Ranitidine
o Ranitidine is a Histamine-2 (or H-2) blocker, which also decreases the amount of acid produced in the stomach. This medication is often given 2-3 times per day orally.
- Sucralfate
o Sucralfate is a medication which binds to unbound proteins, which means that it preferentially binds to areas of the stomach where the superficial lining has eroded. Sucralfate is very helpful in cases of active gastric ulceration, as it helps protect and soothe areas of ulceration. This medication is often given 2-3 times per day orally.
What’s the difference between a preventative dose and a treatment dose of
omeprazole (Gastrogard/Ulcergard?)
In general, the omeprazole dosage for a horse undergoing TREATMENT for gastric ulcers is 4mg/kg (which for an average sized horse is one tube per day) for 30 days. Horses that are in stressful situations or tend to be nervous are given a PREVENTATIVE dose of omeprazole, 1 mg/kg (1/4 tube per day for an average sized horse). Recent studies have shown, however, that the lower doses of omeprazole, though not as effective at treating gastric ulcers as higher dosages, can aid in treatment of gastric ulcers in the squamous portion of the stomach. However, if your horse is diagnosed with gastric ulceration of the glandular portion of the stomach, studies show that only the higher dose of omeprazole are effective at treating these ulcers. Therefore, if some reason (finances or otherwise)is preventing the horse from being treated with a full tube of omeprazole once per day, it is reasonable to treat with a lower dose with the understanding that while this lower dose may help, it will not be as effective as a higher dose.
What is the difference between Gastrogard and Ulcergard?
Ulcergard and Gastrogard both have the same active ingredient; omeprazole. In fact, they even have the same amount of omeprazole in each tube; 2.28g. The difference between the two is in the labeling. Gastrogard is labeled and FDA approved for TREATMENT of gastric ulceration, and the tube is therefore demarcated in lbs, so that owners may dose their horse at the correct treatment dose (the higher dose) for their horse. This usually ends up being 1 full tube. Ulcergard, in contrast, is labeled and FDA approved for PREVENTION of gastric ulceration. These tubes are demarcated by dose, each dose equaling approximately 1mg/kg, or ¼ tube, for the average sized horse. Therefore, if you buy Ulcergard, and give a full tube, it is exactly the same as giving a full tube of Gastrogard. Conversely, if you buy Gastrogard and give ¼ tube, it is the same as giving 1 dose or ¼ tube of Ulcergard.
What environmental changes can I make to help my horse with gastric ulcers?
- Decrease stress
- Allow horses to have constant access to forage (grass or hay)
- Decrease grain and other concentrates
- Increase alfalfa (the high calcium content aids in decreasing the acidic environment of the stomach)