Most owners are aware that horses can suffer from stomach ulcers, a condition which is described by vets as ‘equine gastric ulcer syndrome’ (EGUS). It is not surprising that ulcers are so common in intensively kept horses, because their feeding and management can be so different to that which they have evolved for.
Horses have evolved to eat a high fibre, low-starch diet in an almost continuous pattern, foraging throughout the day and night. Whilst doing so, they live in a herd and move around as they forage. Modern management and feeding practices still often use partial isolation, confinement, high starch diets and limited fibrous forages. Horses are often weaned abruptly and early, and are in intensive training programmes. All of these factors increase the risk for stomach acid build up and the development of ulcers.
Up to 90% of performance horses suffer from EGUS, with racehorses reported as having the highest prevalence, event and endurance horses slightly lower, and show horses a little less. EGUS is also seen in leisure horses at lower rates.
Horses are prone to stomach ulcers because they have an area within their stomach that is unprotected from acid – a non-glandular area – and their stomach produces acid continuously, so there is a risk that the acid builds up and the unprotected area is exposed to damaging levels. Intensive exercise causes splashing of acid on the unprotected area, which is also implicated. Horses can also suffer from ulcers in the protected, glandular part of the stomach. In this case, the cause is thought to be different and is more likely to be related to the use of non-steroidal anti-inflammatory drugs e.g. bute, or to bacteria.
Risk factors for EGUS include a heavy workload, fasting, lack of pasture turnout, high starch intake (from grain-based concentrate feed), restricted fibrous forage intake, no access to water in the paddock, and the use of non-steroidal anti-inflammatory drugs.
Chewing has a protective effect because it produces saliva, which buffers stomach acid, and forage takes many more ‘chews’ and more time to eat, than pelleted or mixed concentrate feed. Horses fed a substantial amount of their ration as concentrate feed will chew less and have longer periods with nothing to eat compared to those fed plenty of forage. Recent research has shown that performance horses can grow and perform well on forage-only diets, providing the forage is high enough in energy. Although some performance horses might benefit from controlled dietary starch intakes, there is no need to feed hard working horses limited forage and high levels of starchy concentrates.
Reducing the risk of EGUS involves managing horses with their natural needs in mind and includes the following:
- Ad lib (free choice) forage, where possible (choose the forage according to the horse’s energy needs)
- Feed appropriate forage to limit necessity for concentrate feed i.e. high energy forage for hard working horses
- No longer than a 4 hour fast
- Plenty of turnout/stabling only when necessary
- Minimal amounts of starchy concentrate feed and a maximum of 1 g of starch per kilo bodyweight per meal
- Free access to water
- Access to forage before exercise (alfalfa is useful due to its high protein and calcium levels)
- Use of stomach-supporting supplements where appropriate (a vet should always be consulted if ulcers are suspected)