EQUINE GASTRIC OR COLONIC ULCERS: WHAT'S THE DIFFERENCE?
We thought that this might be a timely topic and one that seems to come up in question on a fairly regular basis. Ulcers of the intestinal tract are in one way elusive and mysterious in regards to their cause, and yet common enough that we can at least now deal with them appropriately in treatment and "prevention". The important thing to remember is that we group the ulcers into two categories: foregut or stomach, and hind- gut or colonic.
When we say elusive as to the cause, it's because we don't know exactly how the sequence of events unfold in a pathophysiology scenario. For example, we all know that mop water can melt the wicked witch of the west, but we're not too comfortable describing how the top layers of the stomach and large intestine seem to shrivel into a raw and painful puddle. The factors that seem to be common are intermittent feeding (that is, eating at 8am and 5pm instead of grazing throughout the day and night), stress (this can include hauling, showing, training, and a general cluster of psychoses), and intense exercise. The one known and understood factor capable of inducing gastric or colonic ulcers is the administration of NSAIDS (non-steroidal anti-inflammatory drugs) such as bute and banamine. In this case the drug, although intended to inhibit the body's production of prostaglandins causing pain and inflammation, inadvertently inhibits the production of "good prostaglandins" that are responsible for producing protective mucosal layers for the surface of the intestines. As a side note there are now drugs, known as cox-2 inhibitors (Equioxx and Previcox), that selectively inhibit the "bad" prostaglandins while leaving the "good" ones alone; this in turn decreases the formation of drug-induced ulcers.
The clinical signs of ulcers can vary from the subtle to dramatic: poor appetite, chronic reoccurring colic, acute/sudden colic, poor performance, poor or depressed attitude, laying down a lot more than normal, chronic weight loss, stretching or straining often to urinate, and even diarrhea. With foals we additionally see grinding of the teeth, excessive salivation, rolling up on their back, and abdominal discomfort. In regards to the colonic ulcers specifically, signs are similar but can be less dramatic; they include the loss of or poor performance, inappetence/off feed, mild colic, depressed or poor attitude, and in the more severe cases diarrhea and possible swelling or edema under the skin (from loss of protein).
Diagnosis has not always been easy or straightforward. The gold standard of testing for gastric ulcers has been the endoscopic exam, but this not always practical and involves fasting for at least 12 hours; it takes a 2.5 to 3 meter scope to reach the stomach in adult horses. There are no blood tests, although they will occasionally be slightly anemic. Colonic ulceration does usually show some aberrations in the blood work with albumin (the major blood protein) consistently being low (from oozing out of the "scraped knee" surface of the colon), fibrinogen being slightly elevated (an indicator of inflammation), and usually a slight anemia. The large colon is not accessible with the endoscope as it is too far upstream; their small colon (immediately upstream from the rectum, darn near killed-um) is usually not as affected as their large colon.
In the past clinical signs, bloodwork and endoscopy of the stomach (to rule out its involvement) were used to diagnose colonic ulcers. There may also be some acupuncture points that show sensitivity, but this is not always consistent. We do now enjoy a new and simple stall-side test, the Succeed FBT (fecal blood test), which quickly allows us to check for the presence of fecal albumin and hemoglobin (that red stuff in blood), neither of which should normally be in poop. The presence of albumin strongly suggests colonic ulcers (albumin from a stomach ulcer would be absorbed in the small intestines before getting to the exit), while hemoglobin could potentially come from anywhere in the intestines (its sole presence would suggest originating from the foregut/stomach). On a side note there was a recent study to suggest that a heavy parasite/worm burden might give some positive FBT test results, and we could see where this would be especially true around the time of emergence of encysted small strongyles from the colonic walls (October/November for us in the southeast), as well as tapeworms wrecking havoc on the end of the small intestines. We have used this FBT for screening for gastric ulcers and are gaining confidence in its predictability for positive stomach endoscopy exam results; the other path we have taken is combining a positive result with response to therapy. When the albumin fraction of the test has been positive, suggesting colonic ulcers, response to therapy has been very positive and encouraging in correlation with and support of test results.
Therapy involves a multi-faceted approach. Gastric or stomach ulcers are exacerbated by the acidity of the stomach, and so therapy is aimed at increasing the pH (lowering the degree of acidity) so as to promote healing or alternately prevent ulcer formation. As an interesting side-note, we do not culture the H. pylori bacteria associated with gastric ulcers in people; however if there is poor response to typical therapy, then adding antibiotics to the therapy regimen greatly improves results, so go figure. Antacids such as tums and rolaids will very temporarily buffer the stomach, but the means to produce acid is still operational and hence relief is short-lived (about an hour or so). Other drugs such as cimetidine (Tagamet), ranitidine (Zantac), and omeprazole (Prilosec for people and Gastroguard/Ulcerguard for horses) actually inhibit the stomach's production of acid for a set time (24 hrs for omeprazole, 8-12 hrs for ranitidine, and 6-8 hrs for cimetidine). Remember that there is no acid produced in the colon as in the stomach, and hence the acid-blockers used to treat stomach problems have no effect in treating colonic ulcers. With exception there is a drug called sucralfate (Carafate) that sticks to and protects stomach ulcers like a bandaid, and it too will help protect and treat colonic ulcers. We have found two nutraceuticals, Succeed Granules and Smart Digest Ultra, which work very well in treating colonic ulcers. We have noted that after starting therapy (for colonic ulcers) it takes about four months for the FBT to test negative. Both of these products are available online, with the smart-pak product being considerably less expensive; the added perks to these these products is that they both have colic guarantees and will pay between $7500 and $15,000 towards colic surgery should your horse require it whilst on their products (there is some sort of registration process required with each respective company). Smart-Pak also has a product called Smart Gut Ultra that has been shown to be helpful in prevention of reoccurrence of gastric ulcers, but we have still had horses that relapsed while on this product, so additional acid-blocking therapy may be necessary to some degree. For those of you familiar with Gastroguard (omeprazole), the therapeutic dosage for treatment of gastric ulcers is 4mg of drug per kg of body weight; that would be one tube of Gastroguard for a 1250lb horse. The "preventative dose" of omeprazole is 1mg/kg or 1/4th the dose; Ulcerguard is a tube of Gastroguard with a different label, same amount of drug, except it is divided into smaller preventative doses. Misoprostol is a "good prostaglandin" drug that can be used in colonic ulceration to replace the ones that were shut down in NSAID-related side effects. Fats or oils rich in the good omega fatty acids promote mucosal healing, as does psyllium (Metamucil) which indirectly increases colonic fatty acid content and subsequent healing.
Obvious other changes relative to therapy or prevention would include altering management practices so as to mimic natural feeding patterns. This would include more frequent and smaller-portioned feedings (like you don't have anything better to do), less concentrate/grain if possible, and possibly adding alfalfa to the hay menu as it seems to have some unknown, beneficial/protective quality (someone did a study in some race training barns and found that the barns that fed alfalfa, or "flafla" as it is known at the Koella barn, actually had a reduced incidence of gastric ulcers... as many as 65% of the horses of the intense exercise barns had some degree of gastric ulceration). There are some hay-net like bags that will limit how quickly our cows, sorry... horses, will consume a bale of hay; these are wonderful, and the money saved from skipped psycho/therapy sessions will pay for them in no time. Then of course there is the removal or tempering of that insidious "stress" factor, whatever that is; on the contrary one could continue with "the beatings will continue until moral improves" philosophy, but probably not an optimistic or cost-effective approach. Sometimes with colonic ulceration we have to decrease the bulkiness of the diet for 3 or 4 months and let the colon rest by feeding more of a complete, pelleted feed that is less bulky than lots of grass hay. This is obviously balanced in moderation with not letting them fret over nothing to eat, causing stress, and then causing ulcers... just shoot me now.
So in summary, you have another thing to keep in mind when dealing with potential performance and health issues. Both colonic and gastric ulcers can be subclinical or "under the radar" or precipitate in a crisis-type, colic situation. Diagnosis can be direct or procedure/testing oriented, ruled in or out by process of elimination and/or response to therapy, and carefully suspected when a thorough history is explored. Therapy can vary but is very dependent on whether the location is foregut or hind-gut, and it also entails addressing management as well as specific drugs/feed additives. Let us know if you have questions, suspicions, or suggestions.
Jon A. Koella, Jr., DVM Bridlewood Equine