I miss seeing you at the ropings and hope you are feeling better. I rope (in the senior ropings) with an older man that lives fairly close so we have gotten to know each other really well. He trained race horses for many years at the major racetracks, but it seems like he won’t offer any horse advice unless he knows you pretty well. My older heading horse (actually he is only 21 years old) has not been acting just right lately and when I mentioned him to my partner he told me that he has a “sour stomach.” Now, I have been around a while myself but that is a new one on me. What can you tell me about it?
Wow, that term (sour stomach) brings back some great memories (and a few not so great). I first heard the term “sour stomach” about 43 years ago when I first started to practice medicine at the major racetracks. An older trainer (actually he seemed like he was 150 years old to me at that time) stopped me in the shed row and said that his best horse had a “sour stomach” and wanted to know how to treat it. Well, being fresh out of vet school and (at least in MY mind) one of the best vets ever, I was embarrassed to admit that I didn’t have any idea what he was talking about. He was one of the greatest horsemen that ever lived and I did his work on the tracks for many years. He bred and trained several World Champions and we became close friends. During his later years we had some good laughs about his “cocky young vet” that hadn’t even heard of a “sour stomach.” I NEVER DID like admitting that I didn’t know something, but you would think that I would be getting used to it by now.
In all probability those horses that the “old timers” thought had a “sour stomach” had a problem with EGUS (Equine Gastric Ulcer Syndrome). Back then we didn’t have any idea that the ulcers we occasionally found on necropsy of some of the racehorses would ever have a name, let alone medication to treat them.
Clinical signs of EGUS in our equine athletes include attitude changes (they become depressed and listless), poor appetite (failure to consume all of a meal), dullness, reluctance to do their job, decreased performance (working poorly in the arena), weight loss and poor body condition, rough hair coat, tendency to lay down a lot, and intermittent low-grade colic. A presumptive diagnosis of EGUS can be made based on these typical clinical signs and the response of the horse to therapy, but a definitive diagnosis (one that is proven) can only be made using a long video endoscope or a fiberoptic endoscope that is passed through the nose into the stomach of the horse to actually visualize the ulcers.
The stomach of the horse is divided into two distinct areas, the non-glandular region and the glandular region. The non-glandular region accounts for approximately one-third to one half of the equine stomach, is void of glands, and is covered by a tissue known as stratified squamous epithelium that is similar to the lining of the esophagus. The glandular region of the stomach covers the remaining one half to two-thirds of the stomach and contains glands that secrete hydrochloric acid, bicarbonate, pepsin, and mucous. A sharp line of demarcation (called the margo plicatus for all of you scholarly types) separates the squamous mucosa from the glandular mucosa.
Gastric ulcers in our horses are a man-made disease, and management of the horse plays a huge role in the occurrence of EGUS. Ulcers are caused by the erosion of the lining of the stomach, especially the upper non-glandular portion, due to a prolonged exposure to the normal acid (mostly hydrochloric acid) in the stomach. The glandular portion of a horse’s stomach continually secretes this acid, which can result in excess gastric acid when the horse is not eating regularly. This is due to the absence of feed in the stomach to neutralize the gastric acid. Horses are designed to be grazing animals with regular intake of roughage, whether it is hay or grass, and when we prevent this grazing by confinement of the horse in a stall all of the time, the acid stays in contact with the unprotected lining of the stomach and causes the ulcerative erosions or ulcers.
As we mentioned above, the horse’s stomach is divided into two parts. The bottom part is the glandular portion which secretes gastric acid as well as a protective coating (mucous) to keep it from being damaged by the acid. The upper portion of the stomach is designed for the mixing of the contents of the stomach and does not have as much protection from the gastric acid. This upper portion of the stomach (squamous mucosa) is the most common place to find ulcers.
While horses that have EGUS show a pretty typical group of symptoms, the only way to definitively diagnose the condition is by the use of a gastroscope, or a gastroscopic endoscope, and actually visualize the ulcers. The most common length of fiberoptic endoscope that most veterinarians own is 110 cm long. Another type of endoscope is a videoendoscope that is often used in the diagnosis of EGUS appears similar to the fiberoptic endoscope but it has a tiny video camera imbedded in the end of the scope. While the gastroscopes are 110 cm long (about 3 feet), these are over twice as long (3 meters – about 9 to 10 feet).
When viewed through the gastroscope, a normal appearing area of the stomach will be smooth with no reddening of the various areas (Figure 1). The degree of severity of the gastric ulcers ranges from a grade 0 (no lesions as seen in Figure 1) to the worst case scenario, a grade 4 (as in Figure 3). The beginning ulcerations appear as a slight reddening of small areas and would be considered a grade 1 or grade 2. As the lesions become more evident and the squamous mucosa begins to roughen and develop small ulcerations they would be considered grade 3 (as seen in Figure 2). The more severe cases of EGUS will usually be a grade 4 with the ulcers very evident (Figure 3). As you might expect the worse the grade of the ulcers the worse the clinical signs appear to be.
As I mentioned earlier, ulcers are a man-made disease that is related to management and stress of the horse. Stall confinement alone can lead to the development of ulcers. When horses are fed two times per day (or worse, once a day), the stomach is subjected to a prolonged period without feed to neutralize the gastric acid in the stomach. Furthermore, high-grain diets produce volatile fatty acids that can contribute to the development of ulcers. Stress (both environmental stress and physical stress) can also increase the likelihood of ulcers, especially in high strung nervous individuals. Things such as hauling the horse, training the horse and practicing on him, keeping him caged up in a stall rather then turned out to graze, and even mixing groups of horses together can all contribute to gastric ulcers. Strenuous exercise can decrease both the emptying function of the stomach and blood flow to the stomach, thus contributing to the problem of EGUS.
Finally, there is a possibility that the long term chronic administration of NSAIDs (non-steroidal anti-inflammatory drugs), such as phenylbutazone and Banamine, can decrease the production of the protective mucus layer, making the stomach more susceptible to ulcers. The bottom line is this---nearly everything that we do to a team roping horse can contribute to gastric ulcers.
Treatment of EGUS must be aimed toward decreasing gastric acid production and changing our management practices. Multiple medications are available to decrease acid production. The most effective treatment is GastroGard (omeprazole paste, Merial Limited, Atlanta, GA) which decreases acid production for up to 24 hours. The medication contained in GastroGard is omeprazole, the same medication found in Prilosec that is currently prescribed to humans for treatment of gastric ulcers, even though the causes of gastric ulcers in humans differ from those in the horse. Currently, this is the only FDA approved treatment for gastric ulcers in horses. GastroGard is a paste and is given to horses once daily for 28 days to treat EGUS. It is also labeled and marketed as UlcerGard for prevention of recurrence of gastric ulcers at maintenance ½ dose. GastroGard is pretty pricey but it is considered the best treatment available. Other products have been touted as treatments but have not gained acceptance by veterinarians, usually because they don’t work.
Merial Limited, the manufacturer of GastroGard, went around the country from 2008 to 2010 and examined and scoped 3,354 athletic horses and found that EGUS was identified in 58% of those examined. These were horses that were not showing any symptoms of EGUS. In 2010 alone, 644 horses of varying disciplines from 30 different states had some degree of EGUS. Remember that these horses were showing no symptoms. While team roping horses were not included in the study, it was found that 74% of participating racehorses, 60% of participating hunter/jumpers, and 55% of dressage horses were affected. It is only logical that our team roping horses would approximate these figures if they would have been included in the study.
Besides medication to decrease gastric acid production, treatment of gastric ulcers is aimed at removing the predisposing factor. Environmental factors should be addressed as well. Horses that must be kept in stalls (which includes many of our team roping horses) should be arranged so they can see other horses and socialize with other horses. Some horses appear to enjoy having a ball or other object or even a goat or other animal in the stall to occupy their time. Remember some of the tips we discussed several months ago for managing cribbers and stall walkers as many of these same tips are applicable to management of EGUS.
When possible, horses should be allowed free-choice access to grass or hay, preferably while turned out to graze. Actually this turn out is VERY important. More frequent feedings will help buffer the acid in the stomach. If the horse must be stalled all of the time then having good quality grass hay in front of them all of the time is often a good idea. Decreasing types of grain that form the volatile fatty acids may help some horses. The energy from the grain can be replaced by using a feed higher in fat. In horses with lower caloric needs, free-choice grass hay with the appropriate vitamin and mineral supplements will help.
Medication to decrease gastric acid production is only necessary in horses showing clinical disease or when the predisposing factors cannot be removed, as is often the case with horses that we are hauling to ropings. While antacids might sound like a good idea, to be effective they would need to be administered 6 to 12 times a day. Antacids in feeds are also relatively ineffective because they are ingested at the same time as the feed, which will buffer the acid during feeding.
We haven’t been able to examine your heading horse with the “sour stomach” but after hearing the symptoms he was showing, there is a high probability that his problem was actually EGUS (Equine Gastric Ulcer Syndrome). Of course, you should have him examined by your veterinarian to confirm the diagnosis and hopefully, with proper management and treatment, he will no longer show the “sour stomach” symptoms.