Gut balancers and gastric supplements sit side by side on feed room shelves and are often bought for the same horse, sometimes for the same reason. They are designed for different parts of the digestive tract, however, and they contain different kinds of ingredients. A gut balancer is aimed mainly at the hindgut, where fibre is fermented. A gastric supplement is aimed at the stomach. This comparison explains the difference, what each usually contains, when each might be considered and why suspected gastric ulcers always need a veterinary diagnosis first.
Two different parts of the gut
The stomach
The horse's stomach is small and designed for a near-constant trickle of forage. World Horse Welfare describes it as designed for trickle feeding of forage rather than large meals, and advises that some forage should always be present to help prevent ulcers. The stomach lining has two distinct regions: an upper squamous region, which has little protection against acid, and a lower glandular region, which produces acid and has its own defences.
The European College of Equine Internal Medicine (ECEIM) consensus statement on equine gastric ulcer syndrome, published in 2015, treats disease in these two regions as separate conditions: equine squamous gastric disease (ESGD) and equine glandular gastric disease (EGGD). The committee found no relationship between the two, so the presence of one does not predict the other. Read more in our guide to gastric supplements.
The hindgut
The hindgut, mainly the caecum and large colon, is where a large population of microbes ferments the fibre that the horse cannot digest itself. This fermentation supplies much of a forage-fed horse's energy, and it depends on a stable diet and gradual changes. Our hindgut health page explains how sudden changes in feed, grazing or routine can unsettle this system.
What gut balancers usually contain
Gut balancers are designed to support the hindgut microbial population. Typical ingredients include live yeast (most often Saccharomyces cerevisiae), live bacteria in some products, and prebiotics such as fructo-oligosaccharides (FOS) or mannan-oligosaccharides (MOS), which act as food for beneficial microbes. Some products also include yeast cultures, postbiotic ingredients, vitamins or minerals. Our guides to gut balancers and prebiotics and postbiotics explain each ingredient group.
The evidence base is mixed. A 2014 review of probiotic use in horses in the Journal of Veterinary Internal Medicine concluded that evidence for controlling disease with probiotics was weak, while noting that they are generally regarded as safe and easy to give. The same review reported that S. cerevisiae has been shown to survive, but not colonise, the caecum and colon of horses, which is one reason daily feeding is the norm.
What gastric supplements usually contain
Gastric supplements are designed to support the stomach lining, usually by buffering acid or forming a protective coating. Common ingredient groups include antacids and buffers such as calcium or magnesium compounds, pectin and lecithin, plant ingredients such as sea buckthorn, and oils. The ECEIM consensus statement reviewed several of these:
- Antacids give short-lived relief of around two hours or less, so the committee did not consider them justified as a sole therapy.
- Pectin-lecithin products showed no protective effect in two controlled studies, despite promising early reports.
- A product combining magnesium hydroxide, pectin-lecithin and S. cerevisiae showed promise as a preventive for both ESGD and EGGD.
- A sea buckthorn preparation appeared protective against glandular lesions in a fasting model, and corn oil might help reduce the risk of EGGD based on limited pony data.
The overall picture is that some ingredients look promising, but the evidence is limited and none replaces veterinary treatment of diagnosed ulcers.
Side-by-side comparison
| Feature | Gut balancer | Gastric supplement |
|---|---|---|
| Main target | Hindgut (caecum and colon) | Stomach (squamous and glandular regions) |
| Typical ingredients | Live yeast or bacteria, prebiotics such as FOS and MOS, yeast cultures | Antacids and buffers, pectin and lecithin, sea buckthorn, oils |
| How it is designed to work | Support a stable microbial population that ferments fibre | Buffer acid or help protect the stomach lining |
| Typical use | Diet changes, travel, loose droppings with no medical cause found | Ongoing support for horses at risk, often after veterinary treatment |
| Timing | Usually daily with feed | Often with feed or before exercise, depending on the product |
| Diagnosis needed first? | Rule out medical causes of gut signs with your vet | Yes, for suspected ulcers: gastroscopy by a vet |
When each might be considered
Situations where a gut balancer is often considered
Owners usually consider a gut balancer when a horse faces changes that could unsettle the hindgut: a move to new grazing or a new yard, a change of forage batch, travel and competition, or seasonal changes in turnout. Some owners also use them for horses with loose droppings or free faecal water once a vet has ruled out medical causes. A gut balancer supports good management; it does not replace it.
Situations where a gastric supplement is often considered
Gastric supplements are usually considered for horses with known risk factors for gastric ulcers, such as horses in hard work, those on high-starch rations, those fed infrequently, or horses that have previously been diagnosed and treated. Many owners use them during the period after veterinary treatment has finished, with their vet's agreement, alongside changes to diet and routine.
Why a vet diagnosis matters for suspected ulcers
The signs owners associate with gastric ulcers, such as girthiness, poor appetite, dull coat or changes in behaviour, are not specific. The ECEIM consensus statement says clinical signs are nonspecific and poorly associated with the presence of ulcers, and that gastroscopy is the only reliable method of diagnosing gastric ulceration in a living horse. The whole stomach, including the pylorus and the start of the small intestine, should be examined because lesions there are easily missed.
Diagnosis matters because the two forms of disease behave differently. The consensus statement reports that only around 25% of glandular lesions healed after 28 to 35 days of omeprazole, compared with a much higher healing rate for squamous disease. A supplement chosen on guesswork may delay the right treatment, and the signs may have another cause entirely, including hindgut problems, lameness or dental pain.
Management matters more than either product
Both parts of the gut respond to the same basic feeding principles. The ECEIM consensus statement recommends that hay-fed horses receive a minimum of 1.5kg of forage dry matter per 100kg of bodyweight per day, ideally split into four to six meals, and that straw should not be the only forage. It advises keeping starch below 2g per kg of bodyweight per day and below 1g per kg of bodyweight per meal, spacing concentrate meals at least six hours apart and providing water continuously. These steps support the hindgut as well as the stomach. See our article on how much forage a horse needs for practical help.
Can you use both?
Some horses do receive both, for example a performance horse with a history of gastric ulcers that also travels often. Check the ingredient lists for overlap, since some gastric products contain yeast and some gut balancers contain buffers. If you compete, confirm that both brands are members of the BETA NOPS scheme and check your governing body's rules, as some plant-based ingredients can be a concern.
Which should you choose?
- Consider a gut balancer if your aim is to support the hindgut through diet changes, travel or turnout changes, and your vet has ruled out medical causes for any gut signs.
- Consider a gastric supplement if your horse has known risk factors for gastric ulcers or has been diagnosed and treated, and your vet agrees it fits the management plan.
- Choose neither yet if you suspect ulcers but have no diagnosis. Speak to your vet about gastroscopy first.
To see how individual products compare, browse the reviews hub.