Antacid supplements are some of the most popular options for equine gastric ulcer treatment and prevention – but could they be causing more harm than good?

Antacids, such as magnesium hydroxide, are chemical compounds that neutralize stomach acid to temporarily facilitate tissue healing. Excessive acidity in the horse’s gastrointestinal tract can result in ulcers developing as cells of the intestinal wall are eroded away.

Antacids work by counteracting gastric acids, resulting in a higher pH environment in the gut. This buffering effect may result in short-term anti-ulcer benefits. However, because antacids work against the horse’s natural physiology, there is often a rebound effect when a horse stops using them.

In the long run, increasing gastric pH impairs the natural function of the stomach which is to initiate the digestion of feed. This has downstream negative effects throughout the rest of the digestive system.

Long-lasting prevention of gastric ulcers is best achieved by strengthening the barrier function of the intestinal wall and supporting overall gut health.

Simple changes to the horse’s feeding program can have a big impact. These include increasing forage intake and decreasing grain intake as well as providing more frequent, small meals throughout the day.

Avoid equine ulcer supplements that only work to increase gastric pH, either by suppressing acid production or neutralizing stomach acid. Instead, effective supplements for ulcers protect gastric health by supporting the tissues of the stomach lining and maintaining a mucous barrier.

For advice on balancing your horse’s diet to support digestive function and overall well-being, you can submit your horse’s diet for complimentary evaluation by our equine nutritionists.

Understanding Equine Ulcers

Equine ulcers are one of the most commonly diagnosed digestive health conditions in horses, affecting up to 90% of all horses.[1][2]

They are characterized as open sores or lesions that occur along the lining of the gastrointestinal tract. Ulcers can occur anywhere along the gastrointestinal tract, but most commonly in the stomach. [2]

The stomach is divided into two compartments: the squamous (or non-glandular) region and the glandular region. The tissues of the stomach are constantly exposed to acids which are used to break down foods and enable nutrient absorption.

Ulcers in the squamous region are the most common ulcers in horses. Ulcers can also occur in the hindgut and glandular region, but each of these different cites of ulceration are associated with different causes.

Stomach Ulcers Location in Horses

Horses have naturally evolved to constantly produce acids in the stomach, whether there is food to break down or not. This phenomenon is not a cause for concern in the wild, as non-domesticated horses will spend up to 18 hours a day grazing.

However, when horses are not able to graze throughout the day, the stomach sits empty for long periods of time but still produces acids.

In the glandular region, horses have a natural layer of protection that separates the intestinal lining from harsh stomach acids. This area produces mucous and bicarbonate, which forms a protective barrier.

The squamous region of the stomach does not have the same defence mechanism because this region does not produce mucous.

Food, water and saliva buffer the stomach acids. This means that when your horse eats or drinks water, some of the acid in the stomach is neutralized which helps to maintain a stable pH or level of acidity.

A horse that can graze throughout the day can balance their stomach pH level between 2 and 4.

If horses go for more than 3 to 4 hours without food, the stomach pH drops as acids continue to be produced but are not buffered. This creates the perfect environment for ulcers to form.

Given the causal role that excessive acidity plays in the development of ulcers, it is understandable why the use of antacid drugs and supplements is considered to be beneficial for preventing ulcers.

However, this is not an effective long-term therapeutic target. As we will discuss in further detail below, there is a pronounced rebound effect in horses on antacids which can cause recurrence of ulcers.

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