Having the same rider and handler can help reduce a horses risk of glandular disease. | Adobe StockTo understand and, therefore, prevent equine gastric ulcer syndrome (EGUS), horse owners need to understand it encompasses two distinct conditions: equine squamous gastric disease (ESGD) and equine glandular gastric disease (EGGD).Theyre like the odd couple: They both exist in the stomach but dont really have anything to do with one another, said Ben Sykes, BVSc, BVMS, MS, MBA, Dipl. ACVIM, PhD, FHEA, during his presentation at the 2026 EquiSUMMIT Equine Nutrition & Health Conference, hosted by Kemin Industries.How do ESGD and EGGD Differ?Squamous disease affects the lining of top half of the horses stomach, called the squamous mucosa. This tissue, like human skin, doesnt tolerate acid well. Yet the highly acidic gastric juice floating in the lower half of the stomach can splash on the squamous mucosa, causing a chemical burn.In contrast, EGGD occurs in the bottom half of the stomach. Researchers know much less about this disease, but it appears to be stress-based. It is a much more horse-centric disease how the horse perceives and interacts with its environment, said Sykes.Squamous disease occurs very frequently, in up to 90-100% of racehorses. Glandular disease also occurs frequently, in about 50-75% of competition horses, particularly Warmbloods.Understanding and Preventing Squamous Disease in HorsesUnder normal conditions a basketball-sized ball of food floats on top of the highly acidic gastric juice within the horses stomach. The ball stops the splashing effect, decreasing the chances of a chemical burn on the squamous mucosa.The three most important factors that contribute to squamous disease are roughage, nonstructural carbohydrate (NSC) consumption, and exercise, said Sykes.1. Roughage All horses should have sufficient hay available to meet a minimum intake of 1.5% of body weight on a dry matter basis or closer to 2% of body weight on as-fed basis.But we need to appreciate that eating behavior is a complex social behavior for horses, said Sykes. So even horses with unlimited access to hay need to feel safe, secure, and comfortable to eat. So even if they are fed ad lib, measure how much hay theyre actually consuming.While horses benefit from grazing on turnout, Sykes says he prefers for ESGD prevention. Because of the high water content, grass can create a grass soup rather than the roughage ball we want on top of the gastric juice, he said. So even horses on pasture may still need hay and can have squamous ulcers.He also noted that spreading hay in multiple locations, whether in a pasture or a stall, can help reduce overnight fasting and encourage movement that mimics the horses natural grazing behavior.Allowing horses to be social can also influence how much they eat. Horses in groups consume 40% more than horses housed in isolation, speaking to the concept of friends, forage, and freedom.2. Nonstructural Carbohydrates Limit NSCs to 1 gram per kilogram of body weight per meal. If the horse needs more NSCs per day, Sykes recommended providing more frequent, smaller meals. You can also add calories by feeding more fat in the diet. Soaked beet pulp can also help reduce the risk of squamous disease.3. Exercise As horses exercise, the abdomen contracts, causing the acid level in the stomach to rise and allowing it to splash on the squamous mucosa. But its the duration of exercisemore than 30-40 minutes per daynot the intensity, that increases squamous disease risk.In addition, when horses are exercised first thing in the morning, there is no roughage ball on the gastric acid in the stomach, so were going to get a lot of splashing on the squamous mucosa, said Sykes. Feeding alfalfa in the morning will help soak up the acid so it cant splash around.Understanding and Preventing Glandular Disease in HorsesFor most horses, diet is not the driver of glandular disease, but we will still want to reduce NSCs, include alfalfa in the diet, and use oil as an energy source, said Sykes.Overall, a horses environment, along with handling and riding practices, can increase the risk of glandular disease. Affected horses need a limited number of handlers/riders and two to three complete rest days scheduled per week. Also address all confounding stressors such as lameness and saddle fit. We have to treat the whole horse, Sykes said.Reducing stress is also key. Horses benefit from social contact, including the ability to groom one another, he added. Massage and music also benefit horses at risk for developing glandular disease. A decrease in stress-related behaviors translates to increased performance.Take-Home MessageEquine gastric ulcer syndrome consists of two unique conditions, each with its own risk factors. Environmental factors largely drive squamous disease, with prevention centered around optimizing roughage, limiting NSCs per meal, and reducing exercise quantity. In contrast, EGGD reflects internal horse factors; environmental enrichment in the form of friends, forage, and freedom, combined with other stress-relieving measures, might help prevent disease.