Gastric ulcers
Most people (especially those with racehorses or performance horses) are familiar with gastric ulcers. It is essential, especially in these groups of horses, but also in others, that we are aware of the symptoms of gastric ulcers and keep them in the back of our mind when addressing non-specific health and behavioural issues in our horses. Gastric ulcers can seriously impact the health and performance of our horses, and are far more common than you might expect. It is important to identify and manage ulcers for the following reasons:
- Gastric ulcers have been shown in research to have a detrimental effect on the nutritional and general health of horses.
- They decrease appetite and cause weight loss.
- Gastric ulcers can cause colic, which may be life-threatening.
Causes
Horses are trickle-feeders and thus need to eat small amounts of roughage continuously during the day. As they are supposed to feed almost continuously, their stomachs produce acid almost continuously to be ready for the food that arrives. This is quite different to humans, who only produce acid once food is on its way to the stomach.
When grass or hay is eaten, this roughage helps to provide a fibrous mat in the stomach, which prevents acid splashing around the stomach and damaging the lining. If horses are eating continuously, they will also be chewing, which produces saliva that contains bicarbonate that buffers the acid produced by the stomach. Therefore, if the horse does not eat fairly constantly throughout the day, the stomach can become very acidic. Acid is produced continually, but the buffer (bicarbonate in saliva) is only produced when the horse eats, and the fibrous mat is not present to stop the acid splashing around. The high acid level that results from this in the stomach can damage the lining, and it is these erosions of the stomach lining that are called ulcers.
Other possible causes of ulcers include parasites, bacteria and the use of non-steroidal anti-inflammatory drugs (NSAIDs). These may occur separately or in conjunction with the husbandry issues mentioned.
When a horse eats forage, he produces much more saliva than when he eats concentrate. This is because the forage requires much more chewing in order to break it down. Therefore, feeding more forage and less concentrate is better for horses with ulcers, as it increases saliva production.
Statistics from studies:
- Thoroughbreds in race training have a very high prevalence of gastric ulcers (82 to 93% of these horses have ulcers).
- In a study in South Africa, 95% of Thoroughbreds in race training were found to have gastric ulcers.
- Of show horses, 60% have gastric ulcers.
- Of foals with no visible symptoms, 51% have gastric ulcers.
- Of endurance horses, 67% have gastric ulcers.
General symptoms
Symptoms of ulcers are relatively non-specific, meaning that other diseases also cause similar symptoms. It is therefore important to confirm that your horse does indeed have ulcers, not another medical issue.
The most common symptom of ulcers is sporadic colic, especially if the horse seems to exhibit these symptoms directly after a meal. Other symptoms include becoming fussy about food, a decreased appetite and a dull coat. Behaviour changes and performance issues are associated with ulcers, but are not found in all horses.
The most common symptoms of ulcers are as follows:
- Loss of appetite
- Loss of weight or difficulty maintaining weight
- Acute or recurrent colic episodes
- Changes in coat (typically from shiny and smooth to dull and rough)
- Abdominal pain and discomfort
- Diarrhoea
- Wood-chewing, wind-sucking or other stereotypical behaviours
- Development of new and challenging behaviours
- More time spent lying down in the stable or field
- Depression
- Lower performance and achievement levels
It is not uncommon for horses with gastric ulcers to have no clear clinical signs and symptoms. In fact, it has been shown in studies that between 37 and 52% of horses with gastric ulcers show no clinical signs at all. Yet it must be noted that ulcers may still be having a negative effect on performance in these horses.
Risk factors
Certain horses are more predisposed than others to developing ulcers. Whilst ulcers can occur in any horse, certain risk factors lead to this predisposition in certain horses. The proposed risk factors for ulceration of the stomach include:
- Low amounts of paddock time
- NSAID use, such as bute (now illegal in South Africa), given long term
- Horses not being fed sufficient hay or grass
- Horses fed large amounts of concentrate
- High-level exercise but on an intermittent basis (just a couple of times a week)
- Intermittent feeding
- Diet or routine change
- A demanding exercise regimen
- Frequent travel
- Frequent competition
Gastric ulcers can affect horses reasonably indiscriminately, so while risk factors are important, it is not unusual to find an affected horse who spends most of his life as a paddock ornament grazing. Ulcers are not just an issue for the athletic performance horses!
Diagnosis
The only way to really know if your horse has a gastric ulcer is to send him to the vet for a gastroscopy. There are no blood tests that can determine the diagnosis for you. A gastroscopy is an endoscopic examination of the stomach. It is done under sedation and involves a flexible tube fitted with a tiny camera at the end being passed down your horse’s nasal passages into his oesophagus and then into his stomach. Sometimes it is possible for the vet to also visualise the first section of the small intestine (the duodenum) with this procedure.
This procedure will confirm for your vet:
- Whether gastric ulceration is present or not
- Where the gastric ulceration is situated (is it in the upper, squamous part of the stomach or in the lower, glandular part of the stomach?)
- The severity of the ulcers
It is, however, worth noting that not all owners are fortunate enough to have access to a veterinary practice that can perform a gastroscopy – in these instances it may be reasonable to start treatment with omeprazole and observe for improvement in the clinical signs. This is not the gold standard for diagnosis, but is an option in these situations.
Treatment
Omeprazole works by permanently impairing the pump that causes the secretion of acid into the stomach. It effectively switches off acid production so it removes the main cause of the gastric damage, regardless of the cause of the excessive acid present.
There are a variety of treatments available in horses for ulcers, but by far the most effective and commonly used is omeprazole. Below is a list of the potential treatments available in horses:
- Omeprazole, a drug that suppresses the production of gastric acid, is the common first line of treatment for ulcers. It is remarkably effective in most horses and gives the tissue in the stomach the time it needs to heal. The drug also prompts the horse to eat, which reduces the effect of the stomach acid still further. The other advantage of this treatment is that it requires only once-daily dosing, which makes administration easy.
- Ranitidine or cimetidine, which help to reduce gastric acidity, can be given. However, these need to be given at least three times a day to have an effect, and in a recent study of 565 racehorses in training, 96% of the 147 horses receiving these drugs still had gastric ulcers, indicating that the treatment was failing in these horses.
- Antacids can help in the short term, but need to be given every two hours to be effective. It is felt that antacids help in relieving clinical signs, but do not actually heal the ulcers unless acid production is also suppressed with a drug like omeprazole.
- Mucosal protectants, like sucralfate, are recommended to be used in conjunction with the omeprazole. Sucralfate coats and protects the mucosal stomach lining.
- A high-roughage, low-concentrate diet.
- A temporary reduction in the horse’s work and competition schedule.
Prevention
In horses who have previously had gastric ulcers, omeprazole treatment at a lower dose is recommended as a preventative treatment. Studies have shown that if omeprazole is removed entirely after the ulcers have healed, they will over time recur. Keeping a horse on omeprazole long term at a low dose prevents the ulcers from recurring in the vast majority of cases.
Prevention is always the best medicine. We need to accept as horse owners that in removing horses from their natural environment we have stressed their digestive systems to some extent already. It we further add the stresses and challenges of riding, travelling and competing into the mix, it is easy to see how ulcers can arise. Therefore, it is vital that we do everything we can to maintain good digestive health in our horses.
The following management and feeding practices can help in preventing the development of ulcers:
- Providing the maximum amount of turnout possible
- Offering quality forage continuously (24/7)
- Feeding alfalfa, which has been found to be beneficial in buffering stomach acid
- Reducing the amount of concentrate fed
- Using fats as a source of energy and calories in the diet
- Feeding multiple small meals throughout the day (a minimum of three)
- Mixing chaff with concentrate to increase chewing and slow intake
- Using hay nets and slow-feeders to increase chewing and slow intake
Encouraging horses to chew is beneficial in the prevention and treatment of ulcers, as the saliva produced when chewing buffers the stomach acid to some extent.
Take-home message
Gastric ulcers are a common cause of digestive upset in the horse, yet the stomach only makes up approximately 10% of the horse’s entire digestive system! If your horse is experiencing any of the symptoms mentioned above, or other digestive issues, talk to your vet immediately. They will be best to advise you on the way forwards for you and your horse.