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GASTROINTESTINAL ULCERS

November 20, 2017

Many equine athletes travel and compete extensively.  Although they are well managed and their needs for food, water and personal care are addressed in great detail, the stress associated with their activity and attendant travel makes many of them prone to ulcers that affect the gastrointestinal tract. Ulcers can affect the stomach as well as the hindgut, and although some of the clinical signs of the two conditions overlap, other diagnostic and management differences exist.

Why do Horses Get Ulcers?

The precise cause of gastrointestinal ulcers is unknown, and it is likely that it is from an interaction of many factors.  But modern management practices likely play a key role.  Because of practical concerns, most horses do not have access to pasture and grazing for all or most of the day.  Animals that on their own would graze pasture for up to 19 hours per day, are often kept in stalls where they receive 2 sizeable feedings per day, with nothing in between.  As stomach acid production is constant, this means that some of the stomach lining is exposed to acid without some of the benefits of buffering that would come from foodstuffs ingested on a frequent basis.  Many horses are also relatively isolated in stalls without the direct contact of other equine companions they would encounter in a communal pasture situation.  Coupled with stress associated with frequent hauling and competition, this combination of factors is likely important in the recognized frequency of ulcers in horses.

Studies have shown that 60% – 100 % of horses in training develop gastric or stomach ulcers within 2-3 months of going into training.  Thoroughbred racehorses seem to have the highest risk for developing these ulcers.  However there is a relatively high incidence of stomach ulcers even in horses not in active training.  Hindgut or colon ulcers can currently only be confirmed by post-mortem analysis so less information is available for this condition.  However in one study, 44% of non-performance horses and 65% of performance horses were documented to have colonic ulcers.  Both conditions are quite prevalent, so consideration should be given to management practices that might limit their development.

What are the Symptoms?

A number of clinical signs have been associated with ulcers, but in any given case only one or a few may be present.  Many horses develop a poor appetite and become ‘picky’ eaters.  Attitudes often change, with horses showing signs of irritability, nervousness and sometimes aggression.   Some will even show signs of self-mutilation although that is less common.  Body and hair coat condition often deteriorate, and colic signs and diarrhea can also develop. Although no specific cause and effect has been established, performance is often noted to have deteriorated in affected horses.

Diagnosis

Gastric ulcers can be confirmed by endoscopic examination of the stomach (gastroscopy).  Horses need to be held off feed prior to this examination for it to be diagnostic.  Due to anatomic location, colonic ulcers cannot be evaluated by endoscopy.  A commercially available test kit has been developed that assesses blood/blood proteins in the manure, which can also be helpful in diagnosing colonic ulcers.  Some horses will also show edema of the colon wall (in the right dorsal colon) that can be evaluated using ultrasonography.  There are some changes that can be measured using common peripheral blood tests that are compatible with gastrointestinal ulcers, but they are not specific to these conditions.

Management for Horses with Gastrointestinal Ulcers (Alfalfa over Grass Hay)

If possible, avoiding twice daily bulk feeding practices can help minimize the incidence of gastric ulcers.  Pasture turnout however is often limited, so more frequent low volume feedings may be the only way this can be attained.  Management practices may therefore limit this option.  Feeding alfalfa over grass hay is often beneficial as the higher protein of alfalfa over grass hay, along with its relatively high calcium content, can help buffer stomach acids.  If grain or concentrate intake to affected horses is high, feeding more hay is recommended.  It may be that the benefit of more fiber in the hay comes from higher saliva outputs that also help buffer stomach acid.  Any modifications that can be made to a training schedule that might reduce stress should also be considered.  Horses that normally spend considerable time alone in a stall might also benefit from turn out time with other horses.

Treatment of Horses with Gastrointestinal Ulcers

Gastric Ulcers – the most common pharmacologic treatment for gastric ulcers is oral administration of the proton pump inhibitor omeprazole, which impairs the production of hydrochloric acid by the lining cells of the stomach.  The commercial omeprazole product that has been clinically studied is Gastroguard.  This is considered the gold standard treatment for established gastric ulcers.  Another product that also has efficacy is the H2 (histamine)-receptor antagonist ranitidine.  Ranitidine treatment is considerably less expensive than Gastroguard but is not considered to be equally effective in treating naturally occurring gastric ulcers.  Duration of treatment, and monitoring success of treatment should be discussed with a veterinarian, as usually a follow-up plan will be necessary after the pharmacologic treatment period is over.

Colonic Ulcers – there are no specific pharmacologic treatments for colonic ulcers.  The coating agent sucralfate can be helpful in lining the ulcer bed, and stimulating local prostaglandin production that can assist with healing.  Psyllium (Metamucil) may help lubricate the colon contents and speed passage through the colon and thereby decrease the workload on the colonic tissues. Some feel feeding omega 3 fatty acids, as in corn oil, can help decrease the inflammation associated with the ulcers.

Nutraceutical Supplements for Horses with Ulcers

A plethora of supplements have become available for ulcers, unfortunately with little research backing the manufacturers’ claims.  Most of the supplements combine from a few to many ingredients, all of which are theoretically meant to help with either ulcer prevention or treatment.  Some of these ingredients are meant to act as surface coating agents to help protect the lining surface of the stomach or colon.  Others are meant to have local antioxidant and immunomodulatory effects, some are more direct antacids, and others are meant to stimulate local protective mucus production.  Although not truly nutraceuticals, prebiotics and probiotics have also been recommended to help with maintenance of a more normal gastrointestinal tract that would be more resistant to development of ulcers.  More research is required to help delineate which nutraceutical or nutritional ingredients are potentially most beneficial, and which might best target colonic or hindgut ulcers vs gastric ulcers.  

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