The art and science of feeding horses prone to gastric ulcers
/Words - Sarah Nelson
Risk factors for squamous or ‘non-glandular’ ulcers are well documented and include low forage diets and long periods without eating, diets high in non-structural carbohydrate (NSC) or ‘starch and sugar’, intensive exercise and stress, as well as prolonged periods of stabling and travelling. While some risks may be unavoidable for racehorses in training, diet is one that can be influenced relatively easily.
In this article, Nutritionist, Sarah Nelson, discusses some of the science and provides practical advice on the nutritional management of horses prone to non-glandular ulcers. While glandular ulcers may be less responsive to changes in diet, the same nutritional management is generally recommended for both glandular and non-glandular ulcers.
Evidence that diet makes a difference
Research published by Luthersson et al (2019) was the first to show that changes in diet can reduce the recurrence of non-glandular ulcers following veterinary treatment. In this 10-week trial, fifty-eight race/ competition horses were paired according to their workload, management and gastric ulcer score (non-glandular ulcers graded 0-4). One horse from each pair continued with their normal diet while the other had their normal ‘hard feed’ replaced with the trial diet which was divided into three equal meals. Horses with grade 3 and grade 4 ulcers were also treated with the recommended dose of omeprazole for four weeks. All horses were scoped at the start of the trial, immediately after omeprazole treatment had finished and 6 weeks after treatment had stopped.
The majority of horses improved as a result of omeprazole treatment regardless of diet. Diet had no effect on grade 2 ulcers. At the end of the study, gastric ulcer scores in the horses that were fed the trial diet were not significantly better or worse than in horses that were not fed the trial diet. Overall, gastric ulcer scores in horses that were fed the trial diet remained improved 6 weeks after treatment had stopped. Six weeks after treatment had stopped, gastric ulcers scores had worsened in the majority of horses that remained on their normal feed so that overall, there was no difference between pre and post treatment scores.
Importantly, this research shows that changes in diet can help to reduce the risk of gastric ulcers recurring after treatment, even if other changes in management are not possible. There was also no apparent long-term benefit of omeprazole treatment alone, highlighting the importance of other strategies in the long-term management of horses prone to gastric ulcers. As this study only evaluated changes in ‘hard feed’, it is possible that greater improvements could have been achieved if changes to forage were also made.
Recent research reveals unexpected results
Regular turnout often isn’t possible for horses in training and while the risk of gastric ulcers generally seems lower in horses at pasture, recent research carried out in Iceland by Luthersson et al (2022) has highlighted this may not always be the case.
In Iceland, horses typically live out at pasture, often in large herds and if stabled, they are generally fed a high forage, low starch and low sugar diet. While Icelandic horses do get gastric ulcers, it’s been suggested that the over-all incidence is low.
The aim of this study was to investigate the incidence of gastric ulcers in Icelandic horses moving from pasture into light work. Prior to the study, all horses had lived out in large herds for their entire adult lives (age range 3-7 years), had never been in work and were fed supplementary forage in winter months only. All horses were scoped within two weeks of being removed from pasture (prior to starting ‘training’) and were scoped again approximately after 8 weeks of being stabled and doing light work. Most horses were fed forage only during the training period, but 11 were given very small amounts of soaked sugar beet and 3 were given a small amount of commercially produced feed. However, in all cases, starch and sugar intake from ‘hard feed’ was equivalent to less 250g per meal for a 500kg horse which is well within the current recommendations for horses prone to gastric ulcers.
Approximately 72% of horses had non-glandular ulcers (grade 2 or above) at scope 1. The prevalence and severity of gastric ulcers improved after eight weeks of stabling and light work - approximately 25% of horses had non-glandular ulcers (grade 2 or above) at scope 2. Horses given forage three times per day as opposed to twice per day were almost 18 times more likely to improve! Over-all, the incidence of glandular ulcers decreased from 47% to approximately 41%
The high prevalence and severity of non-glandular ulcers at the start of the study, and the subsequent improvement following the training period was unexpected. Not only is this research an important reminder that horses at pasture are still at risk of gastric ulcers, it highlights the importance of regular forage provision.
Forage focus
Forage is critical for mental wellbeing and digestive health in all horses but sometimes receives less attention than ‘hard/ concentrate’ feed, particularly for performance horses. When it comes to reducing the risk of gastric ulcers, one of the main benefits is promoting chewing.
Saliva provides a natural buffer to stomach acid but unlike people, horses only produce saliva when they chew, which is why long periods without eating increase stomach acidity. In one study, the risk of non-glandular ulcers was found to be approximately 4 times higher in horses left for more than 6 hours without forage, although the risk may be greater during the day.
Research by Husted et al (2009) found gastric pH drops in the early hours of the morning, even in horses with free access to forage. Not only do horses generally stop eating/ grazing for a period of time during the early hours of the morning, they are normally less active at night, reducing the risk of gastric splashing.
It should also be remembered that forage is a source of fuel – even average hay fed at the minimum recommended amount may provide close to 45% of the published energy requirement for a horse in heavy exercise. Forage analysis can be a useful tool, especially if you can source a consistent supply.
Routine analysis normally includes measuring / calculating the water, energy and protein content, as well as providing an indication of how digestible the fibre is - more digestible forages yield greater amounts of energy and can help to reduce the reliance on feed.
Minimum forage intake
Ideally all horses, including racehorses in training should be provided with as much forage as they will eat. However large amounts of bucket feed, intense training and stress can affect appetite so voluntary intake (how much is eaten) should be monitored wherever possible.
In practice, this means weighing the amount of forage that’s provided, as well as any that is left in a 24-hour period. Ideally, total daily forage intake should not be restricted to less than 1.5% bodyweight per day on a dry matter basis, although an absolute minimum of 1.25% bodyweight (dry matter) is considered acceptable for performance horses, including racehorses in heavy training.
On an ‘as fed basis’ (the amount of forage you need to weigh out), this typically equates to (for a 500kg horse without grazing):
9kg of hay if it is to be fed dry or steamed (or an absolute minimum of 7.5kg)
11-12kg* of haylage (or an absolute minimum of 9-11kg*)
The difference in feeding rates can cause confusion but essentially, even unsoaked hay contains some water and the water doesn’t count towards the horse’s forage intake.
*based on a dry matter of 65-70%
How much starch and sugar is ‘too much’?
The fermentation of starch by bacteria in the stomach results in the production of volatile fatty acids which in conjunction with a low pH (acidic environment), increases the risk of ulcers forming. Current advice, which is based on published research, is to restrict non-structural carbohydrate (NSC) or ‘starch and sugar’ intake from ‘bucket feed’ to less than 1g per kilogram of bodyweight per meal and ideally less than 2g per kilogram of bodyweight per day. For a 500kg horse, this is equivalent to:
Less than 500g per meal
Ideally less than 1kg per day
Traditional racing feeds are based on whole cereal grains and as a result, are high in starch. By utilising oil and sources of highly digestible fibre such as sugar beet and soya hulls, feed manufacturers can reduce the reliance on cereal starch without compromising energy delivery.
Meal size matters
There are several reasons why horses should be fed small meals but one that’s of particular importance to managing the risk of gastric ulcers is reducing the amount of starch and sugar consumed in each meal.
Large meals may also delay gastric emptying and in turn, lead to increased fermentation of starch in the stomach, especially if cereal based. Restrict total feed intake to a maximum of 2kg per meal which is equivalent to approximately 1 Stubbs scoop of cubes.
Feeding ‘chaff’ to prevent gastric splashing
The horse’s stomach produces acid continuously (although at variable rate). Exercise increases abdominal pressure, causing acid to ‘splash’ onto the stomach lining in the non-glandular region where it increases the risk of ulcers forming. Exercise may also increase acid production.
Feeding short chopped fibre helps to prevent ‘gastric splashing’ by forming a protective ‘fibre mat’ on top of the contents of the stomach and may be of increased benefit to horses on restricted forage diets. Current advice is to feed 2 litres of short chopped fibre volume – equivalent to 1 Stubbs scoop – within the 30 minutes prior to exercise. Ideally choose a fibre containing alfalfa as the high protein and calcium content is thought to help buffer acid.
Supplements safety & efficacy
Supplements are often an attractive option, with owners and trainers from various disciplines reporting benefits. Unfortunately, scientific evidence is currently limited with some studies producing conflicting results which means specific recommendations regarding the optimum blend of ingredients and recommended daily intakes have not been established.
However, ‘ingredients’ that may help to support gastric health include pectin and lecithin, omega 3 fatty acids, fenugreek, threonine, liquorice and maerl, a marine derived source of bioavailable calcium. But don’t forget, there are some important safety considerations, both for horse health and mitigating the risk of prohibited substances.
Supplements should never be used as an alternative to veterinary treatment or an appropriate diet.
Beware of bold claims – if it sounds too good to be true it probably is!
It is illegal for manufacturers to claim products can cure, prevent or treat gastric ulcers. Words like ‘soothe’ and ‘improve’ are also prohibited. While bold or illegal claims do not automatically mean a supplement presents are unsafe, it does raise questions over the company’s ethics.
Speak to a nutrition advisor before feeding supplements containing added vitamins and minerals as some can be harmful (or even toxic) if oversupplied.
Avoid supplements (and feeds) containing added iron.
Be cautious of supplements containing iodine, including naturally occurring sources such as seaweed.
Ensure the total diet provides no more than 1mg selenium per 100kg bodyweight (5mg per day for a 500kg horse).
Natural does not always equal safe – avoid herbs of unknown origin.
In the UK, use only BETA® NOPS (British Equestrian Trade Association, Naturally Occurring Prohibited Substances) approved feeds and supplements.
Only use supplements produced by an authorised feed manufacturer (supplements are classified as feeds in the UK and the EU and regulated by the same legislation). Approval numbers must be included on the label but knowing what to look out for can be tricky. That said, any supplement carrying the BETA® EGUS approval mark will have been produced by an authorised manufacturer.
The BETA EGUS approval mark
Although they are by no means the only suitable option, you can be assured that feeds carrying the BETA® EGUS approval mark have been through a rigorous independent review process to ensure:
The combined starch and sugar content is less than 25% for high energy feeds and less than 20% for low-medium energy feeds
They provide less than 1g of starch and sugar (combined) per kilogram bodyweight per meal when fed as recommended
No inaccurate or medicinal claims are made on the packaging or in marketing materials
The feed is correctly labelled
It fulfils the nutrient specification – this includes independent laboratory analysis
Full references for scientific research available on request.
