Equine Gastric Ulcers – An In-Depth Look

Equine Gastric Ulcers

Equine Gastric Ulcer Syndrome (EGUS) has 2 forms: squamous (ESGD) and glandular (EGGD), based on where in the stomach they are found. All horses can be affected, from foals, competition horses, pleasure horses and even our retired companions can be affected by EGUS.

What are the symptoms of gastric ulcers?

The symptoms of gastric ulcers are often vague and non-specific, but the following are commonly reported:

  • Behaviour change e.g. girthy or grumpy
  • Change in appetite or slowed eating
  • Colic
  • Lethargic or dull
  • Poor performance
  • Poor body condition

How is gastric ulceration diagnosed?

If you have suspicion of gastric ulceration in your horse, based on the symptoms above, speak to your Vet. To make a diagnosis your Vet will perform a gastroscopy (a special camera that is able to look in the stomach and visualise the ulcers). You Vet will grade and describe the ulcers according to their severity and location and will then prescribe a treatment plan as required.

What causes gastric ulcers?

Squamous Ulcers (ESGD) affect the top third of the stomach and tend to be caused by stomach acid splashing on the unprotected lining of the stomach. Risk factors for squamous ulcers include:

  • Daytime forage deprivation and therefore lack of chewing and buffering saliva
  • Lack of access to water
  • High starch diets
  • Straw feeding
  • Intense exercise
  • Change in housing
  • Transport
  • Lack of daily horse to horse contact
  • Stress

Glandular Ulcers (EGGD) affect the lower two thirds of the stomach, where the stomach has glandular tissue lining it. The glandular region of the stomach is responsible for producing gastric acid and has a natural protection from this acid through its mucus coat and presence of bicarb ions. We still have a lot to learn about the cause of this type of ulcers, but our current understanding is that it is caused by failure of the mucus coating.

 

How common are gastric ulcers?

Gastric ulcers are a big issue in competition horses. Racehorses are commonly found to have ESGD with some papers reporting 80-100% of horses in training affected. Research papers have reported that endurance horses during the competition season may have 66-93% of horses affected with ESGD. Horses at home that rarely compete or leave the yard have the lowest risk of ESGD with 11% of horses reported to be affected. EGGD is less well understood but one paper found 54% of leisure horses and 64% of sport horses were affected with glandular ulceration. EGUS not only affects performance, but also affects the horse’s welfare, so clearly we need to do everything we can to support our horses to stay comfortable and ulcer free.

How does Gastric Ulceration affect performance and welfare?

Gastric ulcers are painful. During exercise the pressure in the abdomen increases and the stomach contracts, this in turn can reduce stride length and cause resistance to collection or extension of their stride, likely due to the underlying pain. In jumpers they can also start to cause refusal to jump. This will also limit progression of training and also these horses tend to be quicker to fatigue.

What can you do to reduce the risk of gastric ulcers?

Management and minimizing stress are key, with nutrition playing a key part. The following recommendations can help reduce the risk of gastric ulcers:

Dietary Management:

  • Ensure continuous access to pasture or forage (NB speak to your Vet or nutritionist for advice if your horse is overweight or on a specific diet). This is particularly important during the day (7am to 11pm), due to the horse’s natural circadian rhythm of foraging and typically eating less overnight. It should be noted that adlib supply of roughage does not always ensure horses are eating sufficient, so it is important to note the actual amount a horse eats.
  • Fibre has the benefit of increasing saliva production when chewing, which is a natural buffering effect on the stomach acid, but it also creates a fibrous mat in the stomach which reduces acid splash.
  • If feeding straw as part of a balanced diet in horses or ponies, straw should not be the only forage source and should not exceed 0.25kg per 100kg bodyweight. Please note this rule of thumb does not apply to donkeys, as straw can be an excellent main forage source for donkeys.
  • Feed a small amount of forage or chaff to your horse 30 minutes before exercise, to help form and fibrous mat in the stomach and reduce acid splashing. Just 300g of hay has been shown to have a significant buffering effect.
  • Minimise the amount of starch/grain fed, ensuring each meal is not too large. Replacing some starch-based calories with vegetable oil such as Equine America Supreme Omega Oil may be appropriate. Oil can also be beneficial to gastric health. Your nutritionist or Vet will be able to give you advice specific to your horse’s requirements.
  • If concentrate feed is required, split into 2, ideally 3 meals per day.
  • Encourage natural foraging behaviour by offering forage in different locations in the stable.
  • Ensure constant and free access to fresh water.
  • Supplementary electrolytes are vital for health and performance after sweat loss, but they should not be fed on an empty stomach.
  • Supplements such as Uls-Gard Pellets or Solution can provide targeted nutrition for gastric health and comfort, more on the ingredients later.

Exercise Management:

  • Timing of exercise can be considered, although not always practical! The afternoon is the most sensible time to exercise (for gastric health) as the normal protective mechanisms should be at their peak and the horse should have eaten adequate forage over the morning.
  • Horses prone to EGGD should have at least 2, ideally 3 rest days per week.
  • Exercise should be limited to an average total of less than 40 minutes per day at trot or faster.

Other Management Considerations:

  • Routine is important, try to keep any changes in management to a minimum.
  • Minimise social stressors such as bullying stable mates.
  • Daily turn out at pasture is likely to have benefits, not just from known benefits from the grass, but potentially the increased socialisation (if with a companion) and stress reduction.
  • Ensure your horse has suitable and friendly company in the form of an equine companion to allow horses to display natural behaviours such as grooming to reduce stress.
  • One study in Australia found playing talk radio to their horses increased the risk of ESGD so choose your radio station wisely!!

These recommendations are general, and specific advice relating to your horse or pony should be sought from your Vet and/ or Equine Nutritionist.

What are the key ingredients in gastric support supplements and what is their evidence?

With so many gastric support supplements on the market, it can be overwhelming and difficult to choose! Here are a few key ingredients to look for when making your decision.

  1. Oils

Oils have been used for a long time to support gastric health. Corn oil has dominated the research due to the easy availability in USA. However, oils such as linseed (flax) which are rich in omega 3 fatty acids, have also been shown to be beneficial.

  1. Pectin and Lecithin

Pectin and lecithin support the mucus production in the stomach juices and help form a gel like barrier on the unprotected portion of the stomach wall. They have been shown to have a synergistic effect when combined with other ingredients in a gastric supplement.

 

  1. Prebiotic, Probiotics (saccharomyces cerevisiae) and Postbiotics

The health of the microbiome is key to overall health of the horse, with exciting new developments all the time but this area is huge, and we still have so much to learn. Prebiotics, probiotics and postbiotics have all been shown to confer a health benefit to the horse, and by supporting the microbiome we can support overall wellbeing and performance. The modern horse is subjected to many stresses and challenges that may disrupt the microbiome, such as moving yards (due to the unavoidable changes in forage and herd structure), illness or injury (in particular when antibiotics are required), strenuous training, busy competition schedule and regular travel. All of these have the potential to disrupt the microbiome, with potential implications ranging from a subtle decrease in energy production or reduction in immunity, right through to more serious and obvious consequences such as colic. Pre, Pro and Postbiotics can all help to support and maintain a healthy microbiome.

 

  1. Liquorice

Also known by its latin name, Glycyrrhiza glabra, this ingredient has been used in traditional herbal medicine for over 4000 years to support the gastric mucosal defence factors, but recent research demonstrates that it is still relevant today.

 

  1. Calcium and Magnesium

Calcium and magnesium provide acid ease in the stomach and support a healthy gut pH. The source of the calcium and magnesium is particularly important in horses undergoing veterinary treatment with omeprazole as research has shown that calcium digestibility is improved with a marine algal source (also known as maerl) when compared to other calcium sources.

 

  1. Hyaluronic Acid

 HA is commonly found in joint supplements for its role in synovial fluid viscosity, but recent research has shown the benefits for the stomach, by forming a gelatinous coating on the stomach lining.  

 

  1. Beta Glucans

Beta Glucans are a polysaccharide extracted from the cell walls of yeast, algae and fungi. Beta Glucans have been shown to provide important support for the immune system and overall intestinal health and help in managing the stress response, which is particularly important when travelling. Research has also suggested that it might be helpful to feed to horses before stressful events.

This list is not exhaustive but contains some of the ingredients with the strongest evidence behind them. Research is continuing all the time which our technical team of Vets and Nutritionists constantly review to ensure all our products are up to date and backed by science.

If you want to know more, or would like nutritional advice for your own horse, please speak to our technical team of experienced Vets and Nutritionists.

 

References:

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https://doi.org/10.1016/j.jevs.2022.104088

Balogh, L. et al. (2008) Absorption, Uptake and Tissue Affinity of High-Molecular-Weight

Hyaluronan after Oral Administration in Rats and Dogs. J. Agric. Food Chem. 56, 10582-

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Binda, S. et al. (2020) Criteria to Qualify Microorganisms as “Probiotic” in Foods and

Dietary Supplements. Frontiers in Microbiology. Volume 11, Article 1662.

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Chen, J. and Seviour, R. (2007) Medicinal importance of fungal beta-(1-3), (1-6)-

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Leng, J. et al. (2024) Early-life gut bacterial community structure predicts disease risk and athletic performance in horses bred for racing. Nature, 14: 17124. https://doi.org/10.1038/s41598-024-64657-6

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Pagan, Petroski-Rose, Mann and Hauss (2020) Omeprazole Reduces Calcium

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(2021) Orally administered β-glucan improves the hemolytic activity of the complement

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