Stomach ulcers are major ailment in performance horses

Ulcers develop when the thin stomach lining is lost, leaving the underlying stomach wall exposed.  |  University of Calgary Veterinary Medicine photo

Horses are susceptible to stomach ulcers, especially if they work hard in performance activities such as racing, jumping and showing.

An ulcer develops when the thin stomach lining is lost, leaving the underlying stomach wall exposed. The lost layer normally protects the delicate underlayers from stomach acid and abrasive food items such as coarse grasses.

For an ulcer to develop, there needs to be either increased stomach acid or inadequate protection by the stomach lining.

Some breeds seem to have a genetic predisposition, while other horses may produce too much stomach acid. Stomachs can be damaged from coarse feed and backing up of bile from the intestines.

Bute and related medications reduce the blood flow to the stomach wall, increasing the likelihood of ulcers. Also, stress is another major cause.

Unlike people, stomach ulcers in horses are not associated with the presence of the bacterium Helicobacter.

Horses with stomach ulcers are prone to weight loss, decreased appetite, colic and reduced performance abilities.

A recent study by researchers and veterinarians at the University of Calgary’s Faculty of Veterinary Medicine and the TD Equine Veterinary Group examined horses in the summer of 2014 to tackle this problem. Dr. Sarah Pedersen led the study as part of a two-year fellowship in performance horse medicine at the university.

Before her study, most research into ulcers were in thoroughbred race horses, so it was unknown how often ulcers occur in other performance horses.

The study recruited show jumping warmblood horses in the Calgary area.

“The most pleasant surprise was how well supported the study was by the equine community. These were all privately owned horses and nearly 100 horses were offered to be part of the study,” said Pedersen.

The researchers peered into the stomach of each horse using a three-metre-long endoscope (a long, flexible camera system) to assess the lining for ulcers. They also asked owners a series of questions about management factors such as the amount and type of exercise and intensity, feed, housing and competition level. The study, which was published in the Equine Veterinary Journal, found that 75 per cent of the horses had stomach ulcers.

Their results confirmed the connection between heavy exercise and increased risk of stomach ulcers. Horses that were worked six or more days per week and those in competitions were much more likely to have severe ulcers. This may be related to increased stress with these types of heavy exercise activities. Also, running seems to slosh stomach acid around so that the delicate upper portions of the stomach are exposed to acid.

Another interesting result was that international show-jumping horses were less likely to have severe ulcers compared to those showing at a national level. The reason for this is unknown but the authors suggest that internationally competitive horses may have increased fitness and therefore may experience less stress during competitions. An alternative is that horses who are prone to stomach ulcers are not able to perform at the highest levels.

Feeding beet pulp in this study was associated with fewer stomach ulcers. It may be that the beet pulp increases saliva that buffers the stomach acid or that the additional fibre stimulates the growth of different bacteria in the stomach that protect against ulcers.

It is also unknown how often ulcers affect horses that participate in other performance disciplines such as reining, western pleasure, cattle work and barrel racing.

“They are exposed to travel and competition, so I would expect the amount of stomach ulcers to be reasonably applicable across performance populations. Any performance horse would be at higher risk than a pasture pony,” said Pedersen. “It’s not just thoroughbred racehorses that are affected by stomach ulcers and we need to think about it in all our performance horse populations.”

If you have a horse in heavy competition, it might be worth booking a stomach examination with your veterinarian. If ulcers are present, medications can reduce the damage. As well, based on this study, it might be a good idea to limit exercise to five days per week.

Dr. Jamie Rothenburger, DVM, MVetSc, PhD, DACVP, is a veterinarian who practices pathology and is an assistant professor at the University of Calgary’s Faculty of Veterinary Medicine. Twitter: @JRothenburger

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