Finding the Link Between Behavioral Stressors and Gastric Ulcers in Horses

Gastric ulcers in horses can cause frequent discomfort for our equine friends, with behavioral stressors considered a significant contributing factor to ulcer formation. Horse owners should be aware of how they can help combat these behaviors in their horse. 

What Are Equine Gastric Ulcers?

Horses can develop lesions in their stomach linings called gastric ulcers. These ulcers form due to an imbalance in stomach acid and natural protective buffering.  

When not kept in check, stomach acid can eat through protective stomach lining, causing open sores, or ulcers. This can lead to pain, bleeding, and extreme discomfort in horses.  

Physiological Link Between Stress and Ulcers

To understand why stress leads to ulcers, we need to know what stress does to the body step by step. It’s important to note that there is a difference in the body’s response to acute short-term stress and its response to chronic long-term stress.  

Stress of any kind will stimulate the sympathetic nervous system, which is the fight-or-flight part of the brain. The stimulation, or trigger, of the fight-or-flight response immediately causes the release of epinephrine (adrenaline) and norepinephrine.  

Once in the bloodstream, the adrenaline will circulate throughout the body and cause a domino effect, resulting in a faster heart rate, higher blood pressure, and rapid breathing. This whole chain of events happens very quickly when stress is sensed.  

Acute Stress

During acute stress, the horse reacts to a sudden stressor (e.g., a flying plastic bag, a wild animal coming across their path, or a loud noise).  

Upon sensing the trigger, the brain releases adrenaline into the blood. The adrenaline-filled blood travels to the heart and lungs, resulting in high blood pressure. More oxygen is pumped into the horse’s muscles so they can turn around and run away. 

The physiological response to acute stress causes an increase in acid production in the stomach, exposing the sensitive stomach lining to more acid than normal, causing erosions and damage. Additionally, reduced blood flow to the stomach itself reduces the lining’s ability to heal, leading to gastric ulcer development. 

Prolonged Stress

If stress is prolonged and unavoidable (e.g., a long trailer ride or living in a new location), the initial adrenaline reaction will occur and then fade into stimulating a different part of the brain.  

This other part of the brain is called the HPA axis, and it releases multiple other hormones, including cortisol. Cortisol is responsible for many functions in the body, one of which is metabolism.  

In chronic equine gastric ulcer syndrome, cortisol increases metabolism, which reduces the production of protective mucus in the stomach and decreases blood flow to the stomach lining. These conditions are prime for ulcer development in the horse. 

Behavioral Stressors in Horses

Behavioral stressors are events or situations that lead to emotional and physical responses. As explained above, stress can cause an increase in stomach acid and weakening of a horse’s natural stomach lining, leading to ulcers. 

Examples of behavioral stressors that can lead to equine gastric ulcer syndrome include: 

• Illness 

• Changes in environment (boarding location, barn, stall, or size of living area) 

• Loss of a long-term mate or changes in herd 

• Herd hierarchy imbalance (low on the food chain) 

• Isolation 

• Change in routine 

• Transportation 

• Competition 

• Strenuous exercise 

Some high-stress horses may exhibit behavior issues that correlate with increased stress levels, which can silently lead to gastric ulcers. These may include: 

• Pacing 

• Weaving 

• Cribbing 

• Wood-chewing 

• Head-bobbing 

Horses who perform these behaviors should be checked regularly for signs of gastric ulcers. 

Prevention and Management

It’s important to employ strategies that minimize the things that cause stress and lead to the internal issues that cause gastric ulcers.  

Strategies to reduce behavioral stressors in horses include: 

• Increased turnout  

  • Turnout provides stress-free time for a horse to simply be a horse.  

• Natural grazing 

  • Consistent filling of the stomach helps minimize stress and minimizes the stomach acid’s effect on the lining. 

• Acclimation to changes in conditions 

  • All changes in stalls or herds can be done in slow phases to minimize stress. 

• Social contact with other horses 

  • Having time in a herd is good for a horse’s well-being.  

  • Make sure horses in turnout get along and nobody is getting picked on. 

• Enrichment 

  • Providing slow feed tools or toys to keep horses busy minimizes the time they sit alone and experience stress. 

  • Horses who cannot be in herds can have shatterproof mirrors, so they do not feel alone. 

• Stress-aware training and handling 

  • Horses are more comfortable with calm, confident handlers. 

• Pain management 

  • Long-term pain can cause stress, so work with your vet to control any discomfort and ensure your horse is healthy. 

Nutrition for Ulcer-Prone Horses

Nutrition is a vital puzzle piece in controlling equine gastric ulcer syndrome and helping your horse be their best self.  

Horses are meant to be grazing many hours per day, so a typical twice-daily feeding schedule may not be in their best interest, and has been shown to increase their stress and chances of gastric ulcers.  

Dietary plans to implement to help avoid ulcers include:  

• Frequent small meals or using slow feeders: You can mimic an all-day grazing schedule. 

• High-protein/high-quality hay: Alfalfa is generally a great choice for ulcer-prone horses. 

• Large volume of forage: Include grass hay to increase volume and mimic slow grazing. 

• Excellent hydration: A dehydrated horse is more prone to ulcers. 

• Minimal grain concentrate: Concentrated grains like oats are known to increase the acid in the stomach. 

Work with your veterinarian to formulate the diet that best fits your horse. There are always metabolic concerns to take into account, and every horse is different.  

Your vet can also recommend maintenance medications as needed to help your horse be stress-free and ulcer-free. These may include: 

• Omeprazole 

• Esomeprazole 

• Misoprostol 

• Sucralfate 

Your vet can make specific recommendations or write prescriptions based on what they believe is the best treatment for your horse.  

Many supplements are geared toward healthy stomach lining, stomach acid, and stomach protection to help ward off stomach ulcers. Ingredients like omega fatty acids, beta-glucan, pectin, linseed, aloe vera, and hyaline have been shown to help the acid level and health within the stomach.  

As supplements go, horses can have very different amounts of individual success, so it’s important to work directly with your vet to create long-term health and maintenance that is best for your horse.  

Overall, a horse’s environment and surroundings can be stressful behavioral triggers that increase gastric ulcers. It’s important to watch your horse closely to ensure they are comfortable in their home and herd and have the least stress possible in their daily life.