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STOMACH ULCERS, An Underestimated Threat

Stomach ulcers in horses has, until recently, been a relatively unknown

illness, but further research has brought some eye-opening results to the fore. Endurance Horse speaks to Dr Marc Walton to get to the bottom of this.

How common are gastric (stomach) ulcers in horses? A recent study in the UK proved how much we underestimate the condition. Around 0.5% of foals were presumed to have ulcers; however, after scoping the stomachs of foals an incidence of 57% was found! The incidence even in pleasure horses was found to be 15%. Studies in competing racehorses have revealed an astounding 60–90%. Most relevant to us, a recent study showed that up to 67% of endurance horses have stomach ulcers. The bottom line: most of our competing endurance horses will have some degree of stomach ulcers! Interestingly, only 40% of horses with gastric ulcers show any symptoms. We may be missing them in a number of horses.

How do ulcers develop? Ulcers are easier to understand when you know a little about the anatomy of the horse’s stomach. The stomach’s upper half is a layer of squamous epithelium, similar to our skin. The area has little or no protection, with a high cell repair rate and a thin protective layer being all that separate the cells from acid and enzymes in the stomach. The lower gland-rich half of the stomach has a protective slimy mucus layer and a bicarbonate buffer to bind and neutralise acids before they damage the stomach lining. It makes sense then that ulcers develop mostly in the upper poorly protected regions of the stomach or along the border between the two halves in adult horses. Ulcers develop when there is an imbalance between aggressive (ulcer causing) factors such as acid and digestive enzymes in the stomach vs the protective mechanisms such as mucus (slimy layer), bicarbonate layer, cell regeneration etc. A horse’s saliva also has anti-acid buffering properties. Ulcers are diagnosed and graded by inserting a camera known as an endoscope (“scope”) into the stomach to examine the stomach lining. Ulcers can vary between a grade one (mild redness) to a serious grade four (deep bleeding ulcers).

What causes ulcers? Stress. Just like in people, stress is one of the major causes of ulcers in horses. A stressed horse releases the stress hormone cortisol into the system and this has direct effects on the stomach: increasing ulcer causing mechanisms and decreasing the protective mechanisms. Stress such as strenuous training, racing, transport, stabling illness, surgery and weaning can all cause ulcers.

A normal healthy equine stomach. Note the yellow upper non glandular region and the lower red glandular region separated by a clear line.

The view of a horse’s stomach through an endoscope camera showing severe gastric ulceration. There are deep bleeding ulcers which must be causing severe pain and discomfort. Notice that the ulcers are of the upper poorly protected non glandular region. The first photo is of the same stomach three weeks after “Omeprazole” treatment.

Medications such as anti-inflammatories (eg, Bute) and cortisones are known to cause ulcers due to their effect on the stomach wall. Infections such as rotavirus and salmonella can also cause ulcers in foals. Modern feeding and management practices like large amounts of high energy concentrates, poor quality hay and long intervals between meals are all implicated in ulcers. We put horses in an unnatural situation when we limit their grazing and feed two large concentrate meals a day. This means that instead of the continual flow of food and buffering saliva in a naturally grazing horse, we have a sudden surge of acid and enzymes twice a day. High levels of concentrates in the diet also make the digestive system more acidic, contributing to ulcers.

Why are endurance horses prone to ulcers?

How do I treat ulcers?

Endurance horses are often highly strung and have the added stressors of travelling long distances to rides, contending with new environments and horses as well as the stress of race day itself. They are often fed diets high in concentrates to supply their energy needs.

Vets have the option of using stomach acid pump inhibitors such as omeprazole once a day, or the H2 antagonists such as ranitidine three times a day. Omeprazole has the advantage of being once a day and the horse does not need to stop its training for it to work. There is a withdrawal period before an endurance ride so be sure to consult your veterinarian. Stomach protectants such as ulsanic can also be used, although its effectiveness is under debate. New dietary supplements are available that support and maintain a healthy stomach lining. Supplements containing pectin and glycerine – lectins reinforce the protective mechanisms of the stomach and bind aggressive factors like acids and bile. Supplements such as probiotics help to normalise gut bacteria, which may help in preventing ulcers.

The effect of endurance-type exercise is being studied, with the continual splashing of stomach juices on to the sensitive upper parts of the stomach being implicated in ulcer formation.

What are the symptoms of ulcers in foals? Ulcers can occur in young foals from one day to six months old. They spend less time suckling, salivate, grind their teeth, chew and can show mild to severe colic. Another strange potential symptom is diarrhea. This is a serious disease in foals and can be life-threatening in young foals if left untreated. Remember that ulcers are common in sick foals and vets often treat sick foals preventatively for them.

And in adult horses? In adult horses, the symptoms are more non-specific – the socalled “sad horse”. The horse may perform below expectations, has a poor appetite or even anorexia, lose weight, have intermittent loose faeces or even diarrhea and may have recurrent colic following feeding. Stomach ulcers may be a cause of poor performance in an endurance horse!

How do I prevent ulcers? The bottom line is – minimise stress! Management options can be used to both minimise the risk of developing ulcers and to help heal ulcers in horses with stomach ulcers. A decrease in training levels may help as well as any technique used to minimise stress. Increase the roughage feeding per day and feed smaller concentrate meals more often per day. A new study shows that feeding more lucerne helped to bind acids and prevent ulcers, so consider feeding more lucerne to ulcer prone horses. Dr Marc Walton Ceres Veterinary Hospital


Endurance Horse_Stomach Ulcers: An Underestimated Threat_Jul2010