If you've ever had gastric ulcers or even just bad heartburn, you can sympathize with your horse when he has one of the most common health problems of the stabled horse – gastric ulceration. We humans have the luxury of a quick trip to the drug store for our favorite heartburn remedy, and we can call our physicians for a more in-depth diagnosis of why we experience such agonizing gastrointestinal pain. But horses can only show us by indirect signs that they are in chronic, debilitating pain. How can you understand the signals that your horse is sending you, and understand why he is sending you those signals?
Gastric ulceration in any species refers to an erosion, or sloughing, of one or multiple areas of the surface layer of the stomach. Gastric ulceration is common in horses – in various studies, from 70 percent to 100 percent of horses examined had endoscopic evidence of gastric ulceration. This, however, does not mean that all of these horses had clinical signs of gastric ulceration.
Unlike people, who can develop gastric ulcers in response to a bacterial infection, no infectious cause of gastric ulceration has been identified in horses. In fact, few specific causes of gastric ulceration have been clearly identified. However, most practitioners recognize that stress seems to precipitate gastric ulceration in foals; and infrequent feeds of low-roughage, high carbohydrate foods and a high level of training have been implicated in adult horses.
Unlike humans, horses secrete gastric acid continuously, whether they are eating or not. In the wild, horses spend the majority of their days continually eating small amounts of relatively poor quality, high roughage food. Continual acid secretion accommodates this natural lifestyle perfectly. When horses are fed large quantities of high quality food infrequently, their stomachs empty rapidly, essentially leaving the stomach with nothing to do.
The stomach has a variety of protectant factors against the effects of gastric acid, but when the stomach is empty, the horse's ability to withstand the effects of gastric acid can be overwhelmed. If gastric ulceration becomes severe, the erosions may begin to bleed. Horses can eventually become anemic and low in protein due to losses through the gastric ulcers.
The use of certain anti-inflammatory drugs (such as phenylbutazone ('Bute') or flunixin meglumine (Banamine™) can also induce gastric ulcers in horses.
What to Watch For Recurrent colic
Decreased manure production
Poor body condition
Your veterinarian will take a thorough history to try to identify any risk factors that may have contributed to your horse developing gastric ulceration. In addition, the following may also be necessary: A thorough physical examination. Horses that exhibit symptoms of feed refusal, colic after feeding, weight loss, and do not have a fever, are the usual suspects.
A work-up for colic. If your horse has been showing signs of colic, your veterinarian may choose to perform a work-up for colic, including passing a nasogastric tube and performing a rectal examination to look for signs of intestinal distention or displacement.
Blood tests. Your veterinarian may also choose to take blood tests to make sure that your horse is not anemic or suffering from kidney problems.
Gastroscopy. This is the only way to definitively diagnose gastric ulceration. Gastroscopy refers to the use of a specialized endoscope – a fiberoptic instrument – that essentially allows the use of a camera to visualize the interior of the stomach. Your veterinarian will look for areas of the stomach lining that have an abnormal appearance – this may range from outright areas of bleeding to areas of eroded or thinned tissue.
If your horse has gastric ulceration, your veterinarian will choose to treat with one of a variety of drugs that decrease the acidity of the stomach. He or she will be able to make dietary and training recommendations.
It is important to follow all the instructions given by your veterinarian concerning length and frequency of administration of drugs. Make sure that your horse actually consumes the medications recommended by your veterinarian; it won't help if medications are left in a little pile in the bottom of the feed tub. For some picky eaters, it may be necessary to mix the medication with molasses or applesauce, and syringe it into the mouth.
It is important to monitor your horse's appetite, manure production, and attitude. Most horses will require a high roughage diet and plenty of turnout for best resolution of gastric ulceration.
Horses that have constant access to turnout and roughage in the form of hay or pasture, and horses that are not in training, rarely develop gastric ulceration.
Probably, the best prevention for gastric ulceration is to mimic, as best as possible, the life of a horse at free range. This translates into frequent small meals, a preponderance of roughage in the diet, and plenty of turnout.
Gastric ulceration in horses occurs when acid production overwhelms the protective factors. Unlike the situation in humans, there is no evidence at this point that there is a bacterial cause of gastric ulceration in horses. Infrequent, low-roughage feeding that leaves the stomach empty the majority of the time. This provides a window of opportunity for gastric acid to erode the stomach lining.
Acid production may overwhelm the stomach for various reasons, including:
Intensive training, which tends to go hand-in-hand with infrequent turnout and low-roughage, high-concentrate feeding.
Administration of NSAIDs (non-steroidal anti-inflammatory drugs)
How do NSAIDs cause gastric ulceration? NSAIDs interrupt the production of prostaglandins, which are a diverse family of molecules with extremely diverse effects. You can thank prostaglandins for keeping the blood flowing properly in portions of your kidney, and you can also blame- and thank- prostaglandins for stimulating uterine contractions during childbirth, and for giving you a fever when you have a good case of the flu. By blocking the production of prostaglandins, NSAIDs help to decrease fevers, aches, and pains.
Common NSAIDs given to horses include Banamine™ and Bute (phenylbutazone). As with human beings, NSAIDs are given to treat gastrointestinal pain associated with colic, reduce fever, and to treat inflammation and pain in the musculoskeletal system. Anyone who has had a horse with colic can attest to the efficacy of Banamine™ in decreasing gastrointestinal pain in horses!
One particular prostaglandin, called PgE2, plays an important role in preventing gastric ulceration. PgE2 does this by decreasing gastric acid production as well as by increasing blood flow to the gastric epithelium.
Unfortunately, the NSAIDs that are commonly used in horses don't know that we would like to decrease pain, but retain appropriate blood flow to the stomach. Consequently, we refer to them as non-specific inhibitors of prostaglandins. When we use them to decrease fever, for instance, we also interfere with normal gastric function. The results are multiple – the horse's stomach becomes more acidic, and this contributes to the development of gastric ulceration. Normal blood flow is necessary to healing, and so disruption of normal blood flow leads to a double whammy – not only does the horse develop gastric ulcers, but he also can't heal them very well. It's a vicious cycle. (NSAIDs can also have a deleterious effect on the kidneys, but that is another story).
What are the signs of gastric ulceration in the horse?
Signs of gastric ulceration can be quite hard to pinpoint in horses. Imagine if you couldn't use words to describe how you feel when you have heartburn – you would have to use body language to try to explain the problem. That body language might include lying down more frequently because you're in pain, but then you'd get up again because lying down can make the pain worse. You wouldn't want to eat the foods that you previously enjoyed (even though that might have been a cheeseburger and fries!). You might start to eat, and then stop, because eating makes the pain worse. If you stopped eating the things that are good for you, you might start to lose the gloss in you hair, or become too thin, because you are no longer getting the nutrients that you need. If the pain became intense, you might groan, and hold your abdomen. Well, horses do many of these things, and more. Mild, chronic colic – horses may occasionally look at their sides, lie down more frequently, play with their water, or paw, particularly after eating. A common, and appropriate treatment for mild colic are NSAIDs. However, as we discussed above, NSAIDs themselves can induce gastric ulcers by decreasing blood flow to the stomach and increasing the acidity of the stomach. Without realizing it, you and your horse may have entered a classic vicious circle – the more frequently he has episodes of colic because of the ulcers, the more often he is given NSAIDS – and the ulcers just get worse.
The most common signs of gastric ulceration in horses include:
Less frequently, horses may suffer an acute, severe bout of colic that causes them to really get down on the ground and belly-ache.
Poor condition, especially moderate weight loss. In a typical 1000 pound horse, this usually means weight loss of between 25-75 pounds. This might result in you being able easily to see your horse's ribs. If your horse was on the lean side to start with, with weight loss you might be able to see his hip bones, and his neck may start to look thin and stringy. Because of decreased nutrient intake, your horse might have a coat that looks dull.
Decreased appetite – horses are often reported to eat their hay, but not their grain. Hay takes longer to digest and clear the stomach, so this naturally helps to buffer what is in the horse's stomach. Hay also needs more chewing, and chewing helps to produce more saliva. Saliva is a natural buffer of acids, so, again, this may alleviate some ulcer symptoms.
Decreased manure production – this is usually related to a decreased appetite, and perhaps to decreased gastrointestinal motility.
Poor performance – this may stem from pain. In severe cases, where the gastric ulcers are bleeding, this may also be due to anemia (low red blood cell count).
Signs of gastric ulceration may also be as vague as a change of character, or a 'crabby attitude'. This isn't very hard to understand! Chronic pain is enough to make any horse less cheerful about his work.