Excerpt from Chapter 14 – Digestive Problems
An ulcer is an erosion of the tissue that lines the gastrointestinal tract. It can form anywhere along the digestive tract; however, ulcers are more
commonly found in the stomach and therefore they’re called gastric ulcers. (Colonic ulcers are discussed in the next section.) Cells within the stomach
lining produce a very strong acid known as hydrochloric acid (HCl). It is so strong that if you were to spill some on your hand, it would burn a hole
in your skin. Fortunately, your horse’s stomach is protected by a thick mucous lining (or, rather, part of it is; we’ll look at the stomach in a minute).
Your horse produces HCl continuously, unlike our own stomachs where acid is only produced when we eat. He secretes acid all the time because
he is designed to eat all the time. He is a “trickle feeder,” meaning he is supposed to eat small amounts, grazing virtually 24 hours a day, with intermittent
stops to rest. Eating requires chewing and chewing produces saliva, a natural antacid that neutralizes acid so it doesn’t erode his stomach lining
or have a chance to travel down the rest of his digestive tract, causing more trouble.
HCl sounds like a real nuisance, but it is actually quite necessary. Your horse uses it to start the process of protein digestion. Proteins are very
long, tightly woven, complex molecules that need to be loosened and cut into more manageable pieces before they can be fully digested. HCl relaxes
the protein structure, making the inner portion more accessible to digestive enzymes. And this same acid actually activates an enzyme in the stomach
that starts to cleave off shorter strands of amino acids, a process that will be completed later, in the small intestine.
HCl has another important function — it protects your horse from infections. Horses eat off the ground, taking in mouthfuls of bacteria, viruses,
and an assortment of organisms. Stomach acid is the first line of defense to kill those microbes. This is why I do not like long term usage of medications
that neutralize acid. I’ll discuss those medications later.
So far, so good. So what causes an ulcer?
We do. Ulcers are caused by people. Horses rarely develop ulcers in natural settings. Basically there are four things we do to our horses that cause them
to develop ulcers: We make them work, we cause them stress, we feed them lovingly but improperly, and we give them pain killers that wreak havoc
with their digestive system. I’m here to help you find ways to reduce your horse’s risk of experiencing an ulcer, while still being able to work and perform.
Let’s start by examining each cause separately so you can take steps to prevent this painful condition. And later, I’ll tell how you can recognize, diagnose, and treat ulcers.
REASONS ULCERS DEVELOP
When your horse moves, the acid in his stomach moves with him. To see how this affects his stomach, let’s take a closer look.
Your horse’s stomach is divided into two main regions: the lower, glandular portion, and the upper, squamous area. An ulcer in one of these locations
is referred to as equine gastric ulcer syndrome (EGUS). The upper, squamous region does not have a protective mucous lining.
Looking at the picture above, it’s easy to can see how stomach acid can slosh around to the upper squamous portion when your horse is moving quickly. Events that require speed such as racing, barrels, cutting, or running in general, expose the squamous area to HCl’s caustic effect, creating a nasty sore. This is why most performance horses that run extensively will have an ulcer. In fact, 90% of all race horses have ulcers. Dressage, though a slower, more controlled discipline, involves repetitive movements and rigorous training that also leads to ulcers, but to a lesser extent, affecting approximately 40% of dressage horses.
The lower glandular region, unlike the squamous portion, is shielded from HCl by a thick mucous lining, but ulcers can still form in this area; not
from running but from constant exposure to acid. That’s where stress comes into play.
Stress can take so many forms, I’ve devoted an entire chapter to it: Chapter 17 — Stress and Behavior. You know what stresses your horse. Things
like an unfamiliar environment, a new barn, loss of a buddy, and introducing a new horse to the herd. But there are other stressors, some of which
you may not have much control over, such as stalling, training, performance, and travel. Did you know that ulcers start to show up within three days of your horse’s first exposure to a continuing stressful situation? It may also surprise you to learn that a horse that is moved into a stall after being used to pasture turnout will develop an ulcer in less than a week.
Every horse is different; some become stressed over things that other horses barely notice. But one thing all horses share — they like routine. Any time you make a change, whether it is traveling to a strange location, starting a new training method, using an unfamiliar piece of equipment, or even changing his feed, your horse will respond by producing more stomach acid. If the stressor continues for any length of time, as your horse would experience by sudden stall confinement after living outdoors, your horse’s stomach, specifically the lower glandular region, will be bathed with a continuous supply of acid. This is why stress that lasts for hours or days leads to an ulcer so quickly. And as I’ve pointed out earlier, one of the most common and most preventable situations that predisposes your horse to an ulcer, anywhere along his digestive tract, is standing for hours without anything to eat. Speaking of which, let’s look at the next cause of ulcers.
The best way to avoid an ulcer is to allow your horse to be a horse. And the best way to do that is to give him pasture turnout — the more time, the better.
It not only gives him a steady supply of forage, but it lets him walk around, have a chance to run and buck, and visit with other horses. I realize that it is not always feasible to give your horse all the turnout he wants, but you’ll be happy to know that keeping hay in front of him at all times will go a long way toward protecting his digestive system.
Hay is wonderful. It absorbs stomach acid, requires more chewing which results in more saliva, and buffers stomach acid. In fact, ulcers may be completely avoided by giving your horse alfalfa hay; pellets do not offer as much buffering effect.
I know you understand my point, but you may be up against convincing your horse’s caregiver who may be stuck in old-school thinking. The best advice I can give you is to give this book to that person! I’m not trying to make anyone feel uncomfortable — well, maybe just a little: enough to sway you to change the way your horse is fed.
Do me a favor. You’ve heard me talk about this so much already, I’d like you to take the “Getty Challenge”: Offer your horse all the hay he wants for four weeks and let me know if he’s changed. No, I don’t mean if he’s gotten fatter — I mean his behavior. Is he happier and milder mannered? Does he respond to your commands better and give you his attention? Is he smoother under saddle? Oh, and the weight thing… don’t worry — he’ll eventually eat only what he needs to maintain a healthy weight.
Starch: You may not realize it but starchy feeds can lead to ulcers. Cereal grains stimulate the release of a hormone known as gastrin which tells the stomach cells to produce more acid; furthermore, they stay in the stomach for a relatively short period of time, leaving an empty stomach behind with all that acid. Hay and other fibrous feeds (such as beet pulp, hay cubes, and bran) take three times as long to leave the stomach.
Starchy feed has an additional impact on ulcer development. The stomach’s bacteria (Lactobacillus and Streptococcus) like to start fermenting starch, resulting in different acids — volatile fatty acids (VFAs). This further increases the acid content of your horse’s stomach.
So, in general, 2 lbs of starchy feed at a time is best, but never exceed 4 lbs (weigh your feed!) for an 1100 lb horse. And space your feedings approximately 6 hours apart to prevent accumulation of VFAs. In between those feedings, offer hay — lots of it. And remember the alfalfa; its buffering ability outshines any other hay source.
Enduring pain is stressful and can have the same effect as mental stressors on your horse’s health. But the risk is compounded by overusing nonsteroidal anti-inflammatory drugs (NSAIDs). These medications are often necessary, but they are not meant to be used for more than a few days.
NSAIDs such as phenylbutazone (bute) and flunixin meglumine (Banamine) can irritate the stomach lining enough to set up conditions for an ulcer. They inhibit cyclooxygenase (COX) enzymes. These enzymes stimulate prostaglandin production, which causes inflammation. But not all prostaglandins are harmful. Some are beneficial because they help produce mucus that protects the stomach. I offer a full description of how NSAIDs work along with safe dosing instruction in Chapter 11 — Laminitis.