It has long been recognised that horses, kept in stables and in hard work can become grumpy, and bad tempered, be difficult to girth up and sometimes go off their food. Indeed, when I first qualified over 30 years ago it was not unusual to describe these horses as just “having gone stale, or over the top” and a period of rest or less intensive work prescribed. Other symptoms that we now associate with ulcers range from teeth grinding, to reluctance to go forward when ridden, to colic.
With the advent of specialized gastro scopes for horses, we are now able to see inside the equine stomach and have discovered that ulcers are present in up to 90% of race horses in training, about 60-70% of competition horses and surprisingly in about 30% of horses at grass, which might bring one to suggest that ulcers are almost normal! However, those horses at grass tend to have less severe lesions.
We all recognize that horses have evolved over many thousands of years to roam the plains, and studies on the Brumbies in Australia have seen these animals graze for about sixteen hours a day and travel on average 17 km on route. Wild horses usually move about at slow pace, only galloping when fleeing from danger. They rarely have a prolonged break from grazing and are likely therefore to have some food in their stomachs at all times.
Ulcers are most commonly formed when gastric acid, produced in the lower glandular part of the stomach and a vital part of the digestive system (as it acts to break down the food material at the start of digestion), comes into contact with the lining of the upper squamous part of the stomach for too long a period. As we have domesticated horses, we have altered their diet so that they have more energy for work, which inevitably means more hard feed (grains to provide carbohydrates) and less forage. We have changed their exercise patterns from a steady, day long amble to short periods of intensive activity and long periods of standing in a stable. When the horse is worked on an empty or near empty stomach the acid is splashed upwards and eventually will erode the stomach lining. Stress during periods of competition and travelling can cause reduction in appetite which can compound the problem, and stress itself can indirectly increase acid formation.