Sensitive Stomachs - Gastric Ulcers in Foals and Adult Horses

Gastric ulcers are a very common cause of poor performance, abdominal pain, anemia, poor appetite and lack of thrift in horses. The reported prevalence of gastric ulcers varies depending on the source from 70 – 94% in adult horses and 25 – 57 % in foals. Invariably, horses in heavy training or competition are the most likely to have ulcers. Foals that are ill and/or hospitalized are likewise at greatest risk.

As grazing herbivores, horses produce gastric acid continuously. Under normal conditions, the lining of the stomach is protected by several mechanisms from the effects of gastric acid. Gastric ulcers occur when one or more of these mechanisms malfunctions or is overwhelmed. Our current knowledge of the pathways that lead to gastric ulcer disease is based on studies in humans. Research in horses is ongoing to determine which factors such as diet, exercise, stress, illness and medication affect the ability of the stomach to resist the erosive effects of gastric acid.

The clinical signs of gastric ulcers in horses can be very ambiguous. Colic and loss of appetite are most commonly reported, but many horses with severe ulcers will be completely asymptomatic. Definitive diagnosis of gastric ulcers can only be made by gastroscopy (endoscopic exam of the stomach). Many field practitioners do not have access to this expensive piece of equipment, therefore many horses are presumed to have ulcers and positive response to treatment is considered a positive presumptive diagnosis.

Foals on the other hand display clinical signs that make a presumptive diagnosis fairly easy. In general, most foals that suffer from ulcers also have a concurrent illness or are undergoing severe stress (orphaned foals). Additionally, foals with gastric ulcers will often grind their teeth and roll onto their backs with their forelimbs tucked up. Other signs include diarrhea and poor appetite (failure to nurse).

The treatment of gastric ulcers is a two pronged approach. First, therapy is aimed at decreasing the amount of gastric acid produced. This is accomplished with the use of proton pump inhibitors which block the release of hydrochloric acid into the stomach. There is currently one proton pump inhibitor drug available on the market for the treatment of gastric ulcers in horses. GastroGard (produced by Merial) is a special preparation of the drug omeprazole (commonly known as Prilosec in human medicine). This preparation took years of research to develop. The problem to be overcome was getting the drug past the harsh acidic equine stomach and into the small intestine intact where it could be absorbed. A special microencapsulated form of the drug was developed by Merial to accomplish this. No other oral form of omeprazole is available that will reach the small intestine intact where it can be absorbed. The second aspect of treatment is to protect the already damaged stomach lining using a drug called sucralfate (commonly known as Carafate). This drug forms a gum like substance in the stomach that sticks to the ulcerated and eroded areas forming a kind of plug (think of the Little Dutch Boy with his thumb in the dyke). Treatment is extremely effective, particularly if initiated early.

Clearly the best thing possible is to prevent the development of gastric ulcers. There are several things that may accomplish this task. First, remove horses from their stalls. Stalled horses are far more likely to develop ulcers than horses out on pasture. Regular exercise and small frequent meals (try dividing the concentrate portion of your horses’ diet into 3-4 feedings a day instead of two) will also aid in decreasing the risk. Provide frequent access to hay or pasture throughout the day. Additionally, recent studies performed at Texas A&M University and confirmed by other institutions have shown that horses receiving alfalfa hay as a portion of their ration each day are at decreased risk of developing ulcers as compared to horses that receive grass hay only. These findings were very surprising to the veterinary community. It had previously been believed that a continuous intake of grass hay was the best method of reducing the risk of gastric ulcers. It is now believed that the high level of calcium and protein in alfalfa hay has a buffering effect on gastric juices which helps to protect the stomach. Therefore it is recommended that horses receive at least one or two flakes of alfalfa a day (divided up for each feeding) to help reduce ulcer development. It is also a good idea to provide horses with some alfalfa to consume during trailering. Finally, if you anticipate a stressful situation for your horse (competition, travelling, surgery etc.), UlcerGard, a lower dose form of GastroGard can be used prophylactically to prevent ulcers.

Gastric ulcers in horses and foals are quite common and can pose a very serious health risk. They can also significantly impact the performance and quality of life of the horse. Great advances have been made in our understanding of the prevalence, development, treatment and prevention of gastric ulcers. If you have concerns about your horses’ gastric health or ulcer risks consult your veterinarian for prevention, diagnosis and treatment advice.

In the thick of it.......

Dr. Gordon put up a couple of posts about a test we started at the farm. In her last two posts she details how we started this particular test, now we are right in the middle of working our horses on their exercise program! I made a quick video of the daily workout for our exercise study here at the farm. You can see the horses being set up with a heart rate monitor so that we can see how hard they are working, then see them progressing through a workout. All sixteen horses on the test get work 3 days per week at this stage, we will increase the intensity as they become more fit throughout the test. We had rain all day yesterday so there are a few muddy horses in the picture, but it sure was nice today!