SCIENCE SUPPLEMENTS – Equine Gastric Ulcer Syndrome Part 3

Dr Kirstie Pickles BVMS MSc PhD CertEM(IntMed) DipECEIM MRCVS

Over the last few weeks, we have been looking at stomach ulcers in the horse. Last week we reviewed equine squamous gastric disease (ESGD) CATCH UP HERE . This week we are looking at equine glandular gastric disease in more detail.

Equine Glandular Gastric Disease (EGGD)

Glandular ulcers are less straightforward than squamous ulcers. Research has shown that the lesions we have previously called glandular ulcers, are often not true ‘ulcers’ but are regions of mucosal (stomach lining) inflammation. Therefore, these lesions should perhaps more accurately be referred to as regions of gastritis or inflammation. The exact cause of glandular disease is not yet fully understood. The glandular mucosa of the lower half of the stomach is designed to be in contact with acidic gastric fluid all the time and therefore, unlike ESGD, EGGD is not a simple case of acid injury. Where EGGD develops, it is thought that there is a breakdown in the normal mucosal acid defence mechanism. It is highly likely this breakdown is the result of multiple factors, instead of one single cause. Due to glandular ulcers being unlike squamous ulcers, they cannot be graded by the 1-4 system used for ESGD. Instead lesions are simply described by appearance e.g. flat, raised, depressed, reddened, bleeding etc. (Figure 1).

EGGD can occur alone or with concurrent ESGD. Research has shown that horses with ESGD grade 2 or greater are 5 times more likely to have EGGD than horses without ESGD. Warmbloods appear to be more likely to suffer from EGGD than other breeds suggesting a genetic component to their development. Exercising 5 or more days per week increases the risk of EGGD 10-fold and it has been proposed that exercise could be an example of physiological stress on the glandular mucosa. Increased number of caregivers (more than 3) has also been shown to significantly increase the risk of developing EGGD. Several studies have suggested that stress might play a role in the pathogenesis of EGGD.


Figure 1: Endoscopic views of the inside of a horse’s stomach showing the glandular (G) area of the stomach which includes the pylorus (P) which is the outflow tract to the small intestine. A: Healthy pink glandular mucosa. B: Multiple reddened, raised areas of EGGD with fibrinous membrane covering.

Treatment

Despite EGGD not being directly caused by acid injury, acid suppression is still an important part of treatment of glandular lesions as it is considered that the presence of acid will prevent glandular lesions from healing. Medications used include:

  • Omeprazole: a proton pump inhibitor (often termed a PPI drug) available as a licenced oral paste which switches off acid production. Unfortunately feed lowers absorption of this product so it is best given on an empty stomach (2-3h without food) and at least 30 minutes prior to being fed. Three to four weeks of this paste usually gives excellent healing in squamous ulcer disease but is usually inadequate for glandular healing when used alone and is therefore often used in combination with sucralfate. Treatment for 6-8 weeks or even longer is often required to heal glandular ulcers. An unlicenced injectable omeprazole product is also now available which results in longer acid suppression for 5-7 days. Some studies have shown this product to result in better glandular healing.
  • Sucralfate: an oral product that forms a gel layer over ulcers in an acidic environment and improves blood supply to the mucosa supporting mucus production. It is usually used in combination with oral omeprazole for treatment of glandular ulcer disease. No equine licenced product is available so human tablets can be crushed and given by dosing syringe or an unlicenced paste or powder used from a compounding pharmacy.
  • Misoprostal: an oral product which improves blood supply to the mucosa supporting mucus production and decreases acid production. There is no licenced equine product; human tablets are crushed and given by dosing syringe. This medicine must be stored responsibly and should not be handled by women of child bearing age as it can cause abortion. Some vets have had success with drug whilst others have not.

Management

The previously mentioned risk factors should be minimised in horses with EGGD. Without addressing these issues, ulcers are very likely to return. Management factors to be optimised include:

  • Pasture turnout: The exact role of pasture turnout in the management of EGGD is not clear. Increasing turnout is recommended, but there are certain caveats. Turnout should not cause the horse unnecessary stress (e.g. avoid solitary turnout if the horse does not like this). It is not uncommon for some performance horses to dislike field turnout; standing sulking by the gate is not of benefit to these horses. They would do better in their stable eating hay. Poor quality grazing can act in the same way as food deprivation. If there is not a lot of grass in the field and the horse enjoys turnout, ensure there is additional hay/haylage provided.
  • Access to water: Constant access to water should be implemented at all times. This is hard to do while travelling, which highlights again the increased risk transport poses. Some horses are particular about regional water differences and drink much less away from home. If this is the case, take water from home away to competition.
  • Exercising more than 5 times per week: Although the intensity of exercise performed does not appear to be a risk factor for EGGD, the frequency of exercise is, which is thought to relate to a change in blood supply to the stomach while exercising. Horses with glandular disease should have a minimum of 2 days off work per week, ideally these should be consecutive days.
  • Experience: A young age seems to be an influential factor for the development of glandular ulcers. The likely reason being that older, more experienced horses do not find their job as stressful as younger horses who are less familiar with their role. An inexperienced horse cannot become experienced without work and competitions so design the training and competition routine considerately. Consider the risk that travel and intense exercise pose carefully (acid splash, time without forage and water, intense exercise, lack of rest days).
  • Number of carers: Recommendations are to keep primary carers to two or less people.
    Stress: It is difficult to quantify, and therefore, measure stress, as well as there being great individual variation in what is considered “stressful”. It is important to remember that different horses will find different things stressful, therefore advice on minimising stress must be based on the individual.
  • Anti-inflammatories: When used at recommended doses, for short periods, non-steroidal anti-inflammatory drugs do not increase the risk of glandular ulcers. However, lesions can be seen when these drugs are used at excessively high doses, or for long periods of time. It is sensible to always discuss the use of anti-inflammatory medication with your vet, especially if your horse is at higher risk of developing ulcers.

Additionally, supplements may be useful in ongoing management of ulcer-prone horses. Current research suggests that providing an antioxidant to address oxidative stress within the stomach, buffers/antacids to reduce stomach acidity, and a mucus stimulant are all sensible ingredients for a gastric supplement to contain. Some horses may require a gastric supplement on a long-term basis, whereas others may only need additional support around stressful events, such as travel and competition. Certain supplements can also be used alongside medical treatment.

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