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Equine Gastric Ulcers

Word wide research and studies into equine gastric ulcers have shown that gastric ulcers are prevalent in the horse population. For more than a decade equine gastric ulcer syndrome (EGUS) and colonic ulcers have been linked to performance and health problems in horses, with between 85-90% of racehorses and 75-85% of sport horses affected. More recent studies have indicated that approximately 50% of the leisure horse population may have some degree of gastric ulceration, showing that it is not only horses in high performance situations that are affected. Foals are another portion of the horse population at risk of developing ulcers.

Acidic Environment

Gastric ulcers are the result of erosion of the stomach lining due to a prolonged exposure to digestive acids. In the wild horses graze for up to 16 hours a day and acidity is reduced by the forage and also by bicarbonate in the saliva. If stabled horses regularly have access to hay and grazing, this natural preventative process continues, whereas if they are fed high-concentrate diets with only limited access to forage, the acidity in the stomach increases. Any period without forage intake, whether due to management practices or illness, leads to increased gastric acidity and risk of ulcers. Clinical Signs Signs that a horse may have gastric ulcers can include;

? Attitude change (reluctance to work)

? Poor performance

? Poor body condition

? Reduced appetite

? "Tucked-up" appearance

? Unthriftyness

? Intermittent diarrhea

? Low-grade or intermittent colic

? Possibly wind-sucking and crib-biting

All of the above can provide an indication that an ulcer is highly likely but a definitive diagnosis can only be made using an endoscope to allow the vet to observe the stomach lining in adult horses.

Ulcers in Three Days

Somewhat alarmingly very recent studies in the states (University of Tennessee) have shown that horses can develop gastric ulcers within just three days of a stress condition. Ulcers happen when acidity production exceeds the bodies own protective factors. For gastric ulcers to develop there needs to be exposure to hydrochloric acid (digestive juices of the stomach) and to volatile fatty acids (VFAs) and organic and bile acids (VFAs are fermentation byproducts of sugar sources found in hay or grain, while bile acids reflux from the small intestine). Researchers found that within just three to four hours of exposure to these substances, tissue resistance dramatically decreases. If acid exposure continues, tissue begins to slough away, with severe damage occurring within 12 hours. Saliva is the bodies own buffering system so any changes to a horse's diet that reduces saliva will increase the risk of gastric ulcers.

Stress and Environment

Researchers at Iowa State University, examined the impact of stress conditions on development of ulcers. The study reproduced conditions involved with attending a horse show. The horses were hauled for four hours, stabled in a box stall for three days, exercised on a longe line twice daily, then transported home. Within 5 days seven out of 10 horses had some ulcers. They postulated that if the stress was maintained then clinical signs would start to be seen. The group has also seen horses that live 'on the road' with no ulcers at all, but it is an environment that they are used to and therefore are probably not stressed. It is therefore thought that change is the major factor involved in inducing stress and therefore putting horses at risk of ulcers. Problems start when horses are kept in unfamiliar stables, when their competitive career begins and when being hauled medium to long distances if they are not used to it.

Stress Spotting

It isn't always easy to tell if a horse is stressed. Often a horse that is anxious and nervous doesn't have ulcers, whereas the one that seems placid and calm does. Watch your horse eating; if he eats slowly or eats his feed in several sittings, this may hint that ulcers are a problem. In humans pain usually arises between meals but for horses it seems that meal time and the associated stretching of the stomach causes pain, so apparent discomfort whilst eating and immediately after can be a strong indication that there is a problem.

Saliva Matters

As discussed in previous articles horses are trickle feeders and therefore their stomach produces acid all the time, this means that they need to produce saliva (alkaline) frequently to buffer this acid production. Studies in the UK have shown that horses produce 1ml of saliva per chew. They chew about once every second and take around 4,500 chews to eat a kilo of forage and 1,200 chews to eat a kilo of concentrates. This shows that fibre is crucial to help prevent ulcers as its consumption produces more than 3 times as much saliva. Decreased chewing associated with eating of concentrates results in decreased saliva production and therefore reduced buffering of the acid produced in the stomach. All very painful. Obviously there is even less saliva produced if a horse is left without fibre for a prolonged period of time, again highlighting the necessity for free feeding of forage.

Feeding and Management Recommendations

For horses prone to or suspected of having gastric ulcers the following strategies are recommended;

? Ad lib fibre; minimum of 2% bodyweight for horses in light work, 1.5% for performance horses

? Make use of alfalfa and grass (natural stomach buffers with high calcium content).

Other high-calorie fibre sources will stimulate saliva production and are ideal for the performance horse (alfalfa chaff, grass chaff, sugar beet shreds).

? Keep hay in front of a horse at all times when possible or turn out on pasture to prevent long fasting periods and to keep the horse chewing, which stimulates production of buffering saliva.

? Feed no more than 2kg of grain per feeding and no more frequently than every five to six hours.

? Feeding starch (Oats, barley etc) as an energy source for performance horses is fine as long as enough fibre is fed and the starch meal sizes are small (less than 2kg per meal).

? Minimise stress in your horse's life.

Treatment

Veterinary intervention is usually required to help treat ulcers and many effective medications are available for treatment, the majority of which are similar to medicines used to help treat acid reflux and ulcers in humans.

Preventative and management measures include those above. There are also many 'buffering' supplements on the market but as with all things some will be more effective than others. Calcium carbonate is just limestone and whilst it has some acid buffering capacity the effect only lasts for an hour after feeding and so would have to be fed every two hours (not very practical!). Avoid products which contain a high proportion of this. The majority will contain sodium bicarbonate, which is an effective buffer but again its effect is fairly short lived. Look for products that use sodium bicarbonate in combination with other additives (ranging from seaweed to aluminium based strategies).

Think Fibre

Before using any of these type of products make sure that its claims can be backed up by research. Feeding a buffering agent however is no substitute for managing a horse's feeding program to minimize acid production. Yet another reason to ensure that you think fibre first when looking at your horse's feeding regime.