Equine gastric ulcer syndrome is a condition associated with the inner lining of the oesophagus, glandular and non-glandular parts of the stomach and the initial portion of the small intestine (the start of the duodenum). Gastric ulcers are a common problem particularly among racehorses and elite competition horses, were they can be found in horses of all ages and types. As many as 70.6% of domesticated horses have been found to have ulceration, compared with 29.6% of horses that are allowed to be more ‘feral’. Foals are particularly susceptible with one study reporting as many as 50% of neonatal foals had ulcers.
The clinical signs of gastric ulceration can be very vague and can include; poor performance, mild recurrent colic signs, weight loss or poor condition. The diagnosis of gastric ulceration is confirmed definitively using a gastroscope; a three-meter-long camera, passed up the nose and down the oesophagus of a starved, sedated horse in order to visualise the stomach wall.
There are many causes of gastric ulceration, not all are fully understood and as such, it is too large a topic to cover in this article. In addition the two areas of the stomach that are most commonly, the glandular and non-glandular portions, have different qualities and therefore the disease process is likely to differ between the two sections making it more challenging to fully understand the disease process. In short, gastric ulcers are thought to be caused by an increase in the acidity of the stomach acid and a susceptibility of the gastric lining to damage caused by the stomach acid.
Once a diagnosis of gastric ulceration has been made, the treatment options include changes in the management of the horse, which will be discussed later in the article. The best way to promote healing is using pharmaceutical therapies as it has been demonstrated that only 4-6% of ulcers have been shown to heal spontaneously.
Omeprazole is the only licensed drug for treatment in horses and is the mainstay of treatment, administered usually orally once a day, making it relatively convenient. Omeprazole inhibits the secretion of gastric acid in horses and several other species including humans and dogs. Generally the horse is on a high level of treatment for four weeks, before dropping onto a lower dose for a further four weeks. Generally the horse is then gastroscoped again to assess progress of treatment. Omeprazole begins to work within five days of treatment beginning and has been shown to work in all ages of horse and foals. It is important it is given on an empty stomach preferably 45-60 minutes before a meal, (practically for most horse owners this means first thing in the morning). Omeprazole has recently become available in a weekly intramuscular injection.
Ranitidine is another medication that was previously used horses, it works by preventing the production of acid. Available in a tablet, liquid and an injection it requires administration up to three times a day which is not always practical for all owners. Additionally, the administration of treatment needs to be for between 45 and 60 days, longer than the high dose of omeprazole which can achieve similar healing.
Sucralfate binds to the gastric ulcer forming a protective barrier and encourages production of mucous, another protective layer. Again the frequency of administration is much more often than omeprazole. On its own the sucralfate is not beneficial in the treatment of ulcers however when used in conjunction with other acid-suppressing therapy it can be effective in the treatment in ulcer treatment for the lower part of the stomach.
Misoprostol causes an increase in the pH of the stomach acid from 3.5 to 5 several hours after administration therefore making the acid far less damaging to the stomach lining. Furthermore it causes enhanced mucosal protection by stimulating mucus and bicarbonate production. This has been shown to be more effective in gastric ulcers that have been exacerbated by non-steroidal anti-inflammatory drugs. This drug is currently used for the treatment of ulcers involving the glandular areas of the stomach.
In summary, while there are many treatments available for use in the horse, the mainstay of pharmaceutical treatment continues to be omeprazole in the first instance, with the addition of the other medications in particularly bad cases or in those horses where no significant improvement is seen with omeprazole therapy.
In order to prevent gastric ulcers returning and to aid the above medications in healing, a change in management is an important. These management changes include; as much turn out to grass as possible, continuous access to long fibre while stabled, reduced levels of concentrates, a reduction in stressful situations and to be fed a small meal approximately 20-30 minutes before exercise. Dietary oils have long been added to horses diets, horses fed corn oil have been found to produce more gastric protectants, beneficial in the prevention and treatment of gastric ulceration. Making some minor changes to daily routine have been shown to go a long way in helping to manage these horses.
In short, the therapy for gastric ulceration syndrome has not changed dramatically in the last five years, however what has changed is the education and subsequent recognition of the condition and the subtle signs displayed by individual horses. If you have concerns about the health of your horses’ stomach please do not hesitate to contact the Hospital were we will be happy to talk to you about the options for diagnosis and, if required, resultant therapies.