Gastric ulceration is a common cause of poor performance in horses. An estimated 60% of sport horses suffer from this condition, and suffer is the right word as ulcers cause chronic debilitating pain.

Humans who have experienced gastric ulcers will recognise how painful they are and how they might affect performance in an athlete. Stress, high intensity training and nutritional practices (intermittent feeding of high sugar, low roughage feeds) are recognised factors that contribute to gastric ulcers in adult horses.

In the natural state, horses are constant grazers and their intestinal tract is designed for this kind of feeding. The chewing required for roughage diets stimulates the production of copious saliva which is swallowed and acts to neutralise the acid in the stomach.

Roughage in the stomach also absorbs the acid that is constantly being produced. The surface of the stomach is divided into two zones. One of these contains glands that secrete a mixture of mucus and other substances and form a protective layer against acid. A good blood supply to this zone is necessary to maintain the production of this protective mucus layer. The other surface zone has no such protective layer; it is simply an extension of the lining of the esophagus or food pipe.

When horses are fed only intermittently, and with feeds that stimulate increased gastric acid secretion (high sugar feeds) the stomach empties of food rapidly and leaves acidic fluid behind. Subsequently, when the horse exercises, the acidic fluid splashes up onto the unprotected zones and causes erosions.

Some drugs, like the commonly used anti-inflammatory drugs “Bute” and “Finadine” will exacerbate ulceration. Because they decrease blood supply to the lining of the stomach, these drugs lessen the production of protective factors and decrease the rate of healing for ulcers that are present. These drugs, through the same mechanism, can also cause ulcers further down the intestinal tract.

How might you suspect that your horse was suffering from gastric ulcers? It may be as simple as failure to perform to expectation. Sudden behaviour changes, particularly during exercise or performance, that cannot be attributable to another cause may also occur as a result of the pain associated with this condition. Other more specific signs include unexplained loss of condition, despite excellent nutrition, fussy eating, in particular a horse that is eager to start eating his concentrate feed, but then stops and appears uncomfortable, poor hair coat, low grade recurrent colic and decreased production of manure.

DIAGNOSIS

The only way to definitively know if your horse has ulcers is to have your veterinary surgeon do endoscopy of the stomach, known as gastroscopy. This is similar to passing a camera up the horse’s nasal passages to look at the throat, except the camera is passed further down into the stomach. It is necessary to have a very long scope to reach the stomach; for most adult horses, a three metre scope will give the veterinary surgeon enough length to look around all areas of the stomach and even go into the first part of the small intestine.

The procedure is done standing with just mild sedation. It takes about 20 minutes. The veterinary surgeon will ask you to keep your horse off feed for at least 12 hours before the gastroscopy, as if the stomach is not empty it won’t be possible to see all the relevant areas. Ulcers are usually quite obvious on gastroscopy and are usually seen, in adult horses, at the junction of the two zones described above. Some ulcers may be very superficial; others are deep and may even be bleeding. Some look fairly fresh, others like they have been there a while and are starting to heal. Horses can have one or two ulcers, or many ulcers, and they may be of varying severity, depth and age. There are a couple of different grading systems which can be used to describe the severity of the condition and to monitor the response to treatment.

Once you know your horse has ulcers, the most effective way to treat the ulcers, if you can’t turn the horse out for a month, is with a drug called Omeprazole. This is given to the horse in a paste form once a day for three-four weeks. Omeprazole dramatically decreases acid production in the stomach and is very effective for treating gastric ulcers; however, it is quite expensive. Other drugs that decrease acid production may be used but are considered less effective. Drug therapy alone will not resolve the problem and should be combined with changes in the horse’s nutrition and management. The symptoms should improve after the first week of treatment but it is important to complete the full course as healing takes at least three weeks.

If you know your horse is prone to gastric ulcers, prevention is the name of the game. The best advice is to manage your horse in a manner that most mimics the natural environment. Increasing access to turn out and roughage is crucial, as is minimising stress in the environment.

However, performance is a stressful game. In addition these horses require more energy from their diet than hay alone can provide. Extra energy can be given in the form of fats, such as soya oil added to the diet. There are also a number of supplements marketed for the prevention of gastric ulcers and your veterinary surgeon can advise on which is most suitable to your situation.

Dr Vivienne Duggan MVB PhD Dipl. ACIM & ECEIM is president of Veterinary Ireland Equine Group and is a lecturer in Equine Medicine at the UCD School of Veterinary Medicine.

Email: hq@vetireland.ie

Telephone: 01-4577976