PREVENTING ULCERS

In layman’s terms

by Karen Chaton

August 2005

Introduction

There is one thing about the topic of equine gastric ulcers that I am clear on – the more I learn about it, the more I realize we don’t know.  Most of the studies that have been done have been to show the effectiveness of omeprazole, an effective drug for curing and preventing ulcers.  For a horse with severe ulcers, omeprazole does work extremely well and should be used as a treatment.  However, there are downsides; daily treatment with omeprazole is not only costly, but there are a lot of other questions that arise with its use, such as whether or not a horse receiving omeprazole daily is in violation of the AERC Drug Policy if you stop giving it within 24 hours of a ride. 

Omeprazole works by stopping stomach acid – an important function of the stomach that aids in destroying bacteria that could cause intestinal tract infections such as salmonella.  The altered pH of the stomach may not kill viruses and fungi.  Stomach acid is necessary to digest protein.  The undigested protein moves thru the cecum and large bowel, where fermentation can cause bloating, discomfort and foul smelling manure.   Prolonged acid suppression in humans causes vitamin B12 mal-absorption.  Further human studies have shown an increase in acid production following treatment.  Omeprazole  has been shown to significantly delay gastric emptying in humans, and there are several other potentially serious side effects that have been documented in humans, rats, and dogs (1).  Long-term use in rats has shown thickening of the stomach lining which may or may not predispose for gastric cancer. 

Even if we use the drug to cure our horses’ ulcers, but don’t change any of the management issues that are causing the ulcers – we could face the possibility of having to maintain our horses on omeprazole daily for the life of the horse while it is competing, or, possibly having to retire the horse from competition.  It is especially important for us to learn the best way to manage our horses so that we can help them with the problem of ulcers. 

Causes of Ulcers

·         Extended periods (8-10 hours) with no food

·         Progressively increasing workload  

·         Stress.  Which can include a variety of factors – confinement in a stall, trailering, traveling to new places, changes in feed, etc. 

·         High grain diets  

·         Corticosteroid therapy

·         Anti-inflammatory drugs (such as phenylbutazone ('Bute') or flunixin meglumine (Banamine™)

·         Horses suffering from diarrhea are at increased risk

·         Being a horse!

Symptoms of Ulcers (any of the following)

• Diarrhea
• Low grade colic
• Poor appetite, including the horse refusing foods or supplements that were readily consumed before
• Slow eating, sometimes walking away without finishing meals all at once
• Belching noises
• Decreased performance
• Gradual loss of body condition
• Weight loss
• Pot belly appearance
• Teeth grinding, salivation, froth around the lips
• Lying on their back for prolonged periods

Functional Considerations of the stomach

Adult horses secrete up to 7 or 8 gallons of gastric acid per day, or more than 6 cups per hour.  This is continuous, independent of feed intake and the reason for stomach ulcers. One major cause of gastric ulcers in horses is prolonged exposure of the stomach to high acid levels. The equine stomach is designed for constant feed intake, which provides something for the acid to work on therefore using up the acid.

The stomach of the horse is very small and makes up only 10% of the capacity of the digestive system.  The upper compartment of the stomach is lined with a nonglandular squamous mucosa that is similar to that lining the oesophagus. 80% of equine gastric ulcers occur in this compartment, primarily because it has limited intrinsic resistance to hydrochloric acid and pepsin. The lower compartment is lined with glandular and mucus-secreting tissue. Only 20% of equine gastric ulcers occur in this compartment of the stomach because of its many intrinsic protective properties.

Emptying of the stomach takes 30 minutes for a liquid meal, while complete emptying after a hay-meal can take up to 24 hours. When a horse grazes all day, the roughage he consumes absorbs a considerable amount of digestive acid, keeping the level within the stomach low. In addition, a horse's saliva has an acid-neutralizing effect. As a result, the amount of acid that accumulates in a horse's stomach declines when he's eating and increases when he's not.

Colonic Ulcers Significant Risk for Performance Horses.

In a study conducted by Frank Pellegrini, DVM, 63% of horses involved in competition sports – ranging from dressage to racing – suffered from colonic ulceration.

Pellegrini’s work confirmed the findings of earlier studies, showing that 87% of horses have gastric ulcers (ulcers of the stomach). When combined with his findings on the lesser-understood issue of colonic ulcers, however, Pellegrini’s study yielded some new information. He found that 54% of performance horses suffered from both gastric and colonic ulcers. Further, Pellegrini’s study showed that 97% of performance horses had some type of ulceration.

“This research suggests that ulceration in the colon may be to blame for the low grade anemia, colic and other conditions seen frequently in high performance horses,” said Pellegrini. “Most importantly, it brings into focus the need for further research on the direct causes of colonic ulcers and how exactly they affect the horse.”

Pellegrini’s research proves that colonic ulcers exist prevalently within the performance horse population. Unfortunately, no treatment now available can cure them. Omeprazole, used for gastric ulcers, was formulated for the specific conditions found inside the stomach and will not positively affect the delicate colonic environment.

“Given that more than 60 percent of all performance horses may be suffering from colonic ulceration – which cannot be treated with traditional ulcer medications – it may be time for equine caregivers to consider other options,” said Pellegrini. “A dietary supplement intended to maintain optimum digestive tract health may be the best solution to preventing colonic ulcers before they negatively affect performance and attitude in the horse.”

One approach to promoting overall digestive tract health involves the use of non-testable, natural foodstuffs to heal the intestinal tract and support good health throughout this critical system. Here is a quick summary of some substances and how they may work to help keep the horse’s gut healthy:

• Beta glucan is a dietary fiber found in oats and barley that has been shown to slow down the movement of feed through the gut, allowing excess starches to be digested before they enter the colon. Beta glucan is also a powerful immune stimulant, encouraging the horse’s immune system to attack any bacteria that might otherwise enter an ulcer.
• Polar lipids are found in specially processed oat oil. Lipids (or fats) help to protect the lining of the gut. Polar lipids are emulsifiers ­ they help water and oil to mix, and therefore allow certain oil-soluble vitamins, such as A, D, E and K, to be absorbed by the gut.
• Glutamine is a natural amino acid that may help the gut renew and heal itself. It is “conditionally essential,” ­meaning that the body cannot produce enough of this amino acid when it is undergoing stressful situations, such as heavy competition training. Glutamine assists the cells of the gut to grow close together, keeping out dangerous micro-organisms.
• Threonine is another amino acid. It is “essential,” ­meaning that the body doesn’t produce enough on its own, so it must be supplied in the feed. Threonine is needed for the creation of mucus, which lines the stomach and intestines, protecting them from acidic digestive juices.
• Yeast sugars called mannan oligosaccharides (or MOS, for short) help the immune system to get rid of bad bacteria. MOS also absorb dangerous toxins so they can be safely excreted.  (Pellegrini, Franklin L. 2005)

Prevention and Recommendations. 

·         Respect the function of the gut!

·         Turn horses out as much as possible so they can graze

·         Don’t feed a lot of grain

·         If grain must be fed in large amounts, divide feedings so that no more than three pounds is given at any one time.

·         Avoid prolonged periods of fasting – ulcers can develop within 10-12 hours when horses have no access to feed

·         Keep roughage available at all times.  Horses need to eat continuously

·         Provide free choice grass hay at all times

·         Feed frequent small meals – optimum is 4 times a day

·         Place feed bins on the ground – horses chew and swallow more efficiently when their heads are down and the throat extended

·         Use steam-extruded feeds which have been processed in such a way that eating is slower, resulting in more chewing, increased saliva production and higher saliva bicarbonate levels

·         Match your horse with a job he enjoys and is well suited for

·         Gradually increase training schedule

·         Ride conservatively until you know your horse handles competition

·         Provide as much exercise and entertainment as possible.

·         Provide Probiotics on a daily basis if your horse is in training or confined due to injury or illness

·         Avoid frequent or long-term use of non-steroidal anti-inflammatory agents

·         Tapeworm infestation can mimic symptoms of ulcers. Be sure to worm with a wormer that gets rid of tapes 

·         Add ¼ cup of corn oil to your horses diet daily

·         Bananas are a high energy feed and they also contain high levels of phospholipids that can assist in lining the horse's stomach and preventing acid damage to the stomach

·         Papayas are another natural way to help horses with ulcers.  Papain stimulates the appetite, soothes membranes of the esophagus and stomach and quiets inflammatory bowel disorders. Raw papain is used medically for enzyme replacement in pancreatic insufficiency and has anti-microbial, anthelmintic and anti-ulceratial effects. http://www.stomachsoother.com

·         Horse owners have reported anecdotally that a cup of aloe vera juice twice a day helped their horses ulcer symptoms go away

·         Horses should be fed no less than 50% (and preferably >70%) of their dry matter intake as long dry hay or pasture

·         Feed a small amount of alfalfa (2-3 pounds once or twice daily), the calcium may buffer stomach acid

·         Keep your horse in good body weight and a good body condition score

·         Check out other non-antacid type ulcer products:  http://www.horse-journal.com/newspics/pdfs/12-3-Non.pdf

Research

All but the last 2 listed projects as well as Pellegrini’s work above were done on other than endurance horses.  When race horses were studied well over 90% had ulcers.  The incidence of ulcers in Endurance horses is as low as 50%, probably because of the closer relationship between horse and care giver along with management practices that are shown to be less likely to cause ulcers. 

Benefits of Corn Oil Supplementation.  Ponies fed a free-choice hay diet for 5 weeks, which was followed by 5 weeks of the same diet supplemented with 45 mL of corn oil daily. The study concluded that corn oil supplementation may be an effective and inexpensive way to increase the protective properties of equine glandular gastric mucosa. (Cargile JL et al. 2004)

Effects of exercise on gastric volume and pH in the proximal portion of the stomach of horses.  Increased intra-abdominal pressure during intense exercise in horses causes gastric compression, pushing acidic contents into the proximal, squamous-lined region of the stomach. Increased duration of acid exposure directly related to daily duration of exercise may be the reason that squamous lesions tend to develop or worsen when horses are in intensive training programs.  (Lorenzo-Figueras M et al. 2003) 

Prevalence of gastric ulcers in show horses. Gastric ulceration was detected in 58% of the horses. Horses with a nervous disposition were more likely to have ulceration than quiet or behaviorally normal horses. Horses with gastric ulceration had significantly lower RBC counts and hemoglobin concentrations than those without ulceration.  (McClure SR et al. 1999)

Do age or sex matter?  One study on 224 Standardbred racehorses in training concluded that although there was little association between age and prevalence of ulcers, there was an association between age and severity of ulcers. Most 2-year-old horses (57.7%) had an ulcer score of 0 or 1. In all other age groups, most (58% to 82.61%) of horses had an ulcer score of 2 or 3. Although overall prevalence of ulceration was comparable among sex groups, the relative risk for gastric ulceration increased with age in castrated males, whereas it decreased in females and sexually intact males. (Rabuffo TS et al.. 2002)

Gastric ulcers in Standardbred racehorses: prevalence, lesion description, and risk factors. The number of lesion sites (P < .0001) and poor body condition (P < .0001) were significantly associated with lesion scores. Gastric ulcers are highly prevalent in Standardbred racehorses. Furthermore, actively racing horses and trotters are more likely to have gastric ulcers. Also, poor body condition in Standardbred racehorses may be an indication that gastric ulcers are present and that lesion scores are high. The cause-and-effect relationship between poor body condition and the presence of gastric ulcers is unclear.  (Dionne RM et al. 2003)

Evaluation of urine sucrose concentration for detection of gastric ulcers in horses. Urine sucrose concentration appears to be a reliable but imperfect indicator of gastric squamous ulcers in horses. Sucrose permeability testing may provide a simple, noninvasive test to detect and monitor gastric ulcers in horses. (O’Conner  et al. 2004)

Effects of intramuscular omeprazole on gastric acid secretion in horses over a twenty-four hour period. Due to the simplicity of the administration technique and the higher biological availability, intramuscular administration may offer a practical and less expensive way of treating gastric ulcers in horses. (Sandin A et al. 1999)

Effects of intermittent feed deprivation, intermittent feed deprivation with ranitidine administration, and stall confinement with ad libitum access to hay on gastric ulceration in horses.  Severe ulceration of the gastric squamous epithelial mucosa, caused by excess acidity, can develop rapidly in horses deprived of feed or not consuming feed. Suppression of gastric acidity with the histamine type-2 receptor antagonist ranitidine effectively minimized the area of ulceration caused by feed deprivation. Compared with being turned out to pasture, stall confinement alone appears to be an important factor in the development of gastric ulcers in horses, probably as a result of altered eating behavior.  (Murray MJ et al 1996)

Gastric ulcers in horses: a comparison of endoscopic findings in horses with and without clinical signs. Gastroendoscopic examinations were performed on 187 horses, ranging from one to 24 years. Eighty-seven horses had clinical problems including chronic, recurrent colic for seven or more days (25), one or more episodes of colic within the previous seven days (13), or acute colic (10), diminished appetite (53), poor bodily condition (40), and/or chronic diarrhea (9). One hundred horses that had no signs of gastrointestinal problems were examined as part of a gastroendoscopic survey. Lesions observed in the squamous fundus, squamous mucosa adjacent to the margo plicatus along the greater curvature, glandular fundus, and the squamous mucosa along the lesser curvature were scored on a scale of 0-4, with 0 representing no lesions and 4 representing the most severe lesions. The mean endoscopic scores for the squamous fundus, margo plicatus and lesser curvature were significantly greater (P < 0.001) in horses with clinical signs than those without signs. This was because of the greater number of horses with lesions in the symptomatic group (80/87) compared to those without signs (52/100), and the greater severity of lesions in the horses with clinical signs. Of the horses, 74 were in race training. There was a significantly (P < 0.01) greater prevalence and severity of lesions at all sites except the glandular fundus in horses in training compared to those not in training, and in the horses in training with clinical signs (n = 37) compared to those in training without clinical signs (n = 37).  (Murray MJ et al. 1989)

Comparison of endoscopic, necropsy and histology scoring of equine gastric ulcers.  Only 1/23 horses had glandular ulcers observed via endoscopic examination whereas, 6/23 horses had glandular ulcers at necropsy and on histopathology. The prevalence of EGUS is high in stalled yearling horses. The endoscopist may underestimate the number of gastric ulcers and may not be able accurately to predict the severity or depth of those ulcers present in the nonglandular equine stomach. Furthermore, the endoscopist may miss glandular gastric ulcers. (Andrews FM et al 2002)

Evaluation of diet as a cause of gastric ulcers in horses.  An alfalfa hay-grain diet induced significantly higher pH and VFA concentrations in gastric juice than did bromegrass hay. However, number and severity of nonglandular squamous gastric lesions were significantly lower in horses fed alfalfa hay-grain. An alfalfa hay-grain diet may buffer stomach acid in horses. (Nadeau JA et al. 2000)

Histological characteristics of induced acute peptic injury in equine gastric squamous epithelium.  Erosions and ulcers were induced in equine gastric squamous epithelium using a feed deprivation protocol that results in prolonged increased gastric acidity. Specimens of normal gastric mucosa and mucosa with lesions created after 48 and 96 h of feed deprivation were compared for characteristics associated with angiogenesis and mucosal proliferation.

These findings demonstrate that processes that promote ulcer healing begin soon after peptic injury and that they progress even with repeated peptic injury. Furthermore, our findings support observations that gastric ulcers often heal without medical intervention, and the theory that medications that reduce gastric acidity do not initiate healing, but rather facilitate ulcer healing by providing a microenvironment that is optimal for healing to proceed.  (Murray MJ et al. 2001)

Prevalence of gastric ulcers in endurance horses – a preliminary report.  Gastric endoscopy was performed at the end of a 50 or 80 km endurance ride. Gastric ulceration was evident in 67% of the horses with ulcers on the squamous region of the stomach found in 57% of the horses and active bleeding of the glandular mucosa in 27%. Three horses (10%) had lesions only on the glandular mucosa. Values of albumin, creatinine and glucose were higher in horses without gastric lesions. We conclude that horses from endurance competitions have a high prevalence of gastric ulceration that is similar to that observed in performance horses. However, the severity of ulceration is less severe than has been reported in Thoroughbred race horses in active training. Owners should be aware of the high prevalence of gastric ulceration in horses that perform in endurance competitions. The high incidence of active bleeding from the glandular mucosa of the stomach in these horses requires further investigation.  (Nieto JE, et al. 2004)

Incidence of Gastric Ulcers in Active Endurance Horses.  A study that looked at 92 horses in 8 states, that were actively involved in all aspects of Endurance Riding and were between rides.  The researcher believed that it was important to look at the horses when they were not under the stress of an event, eliminating the horses that simply showed signs of gastritis from the event itself.  Forty seven or 51% had some degree of ulcers (grade 1,2 or 3).  Thirty one or 33.7% showed grade 2 and 3 ulcers which are considered clinical lesions.  Eleven or 11.96% of the horses had grade 3 bleeding ulcers.  (Fleming 2005, see complete study in this issue of EN)

Conclusions

Some horses may still need to receive medication and veterinary care in order to heal and prevent ulcers.  Many horse owners cannot afford to spend upwards of $1000 per month, or even half that every month in order to keep their horse competing.  Hopefully some of the information provided here will be able to help those that want to find other ways to prevent a problem that seems to have a high prevalence in our horses.  Remember that every horse is an individual and what works for one may not work for another. 

During the process of compiling this information, I was able to ask Dr. Scott of UCLA (a researcher on EGUS) several questions on this topic.  Below is a summary of his advice:

“I suggest that unless the animal is showing signs of distress and appears happy and healthy despite having a positive endoscopy for gastric ulcer, do nothing. If the animal is suffering by all means use gastrogard and withhold the drug prior to competition. The drug should clear the blood in a few
days.

Most horses will have ulceration in the epithelium above the margo placatus. Many fewer horses have ulcers in the fundus and antrum which are more worrisome. Again if your animals seem happy and healthy, don't have them scoped since what you don't know won't bother you or the horse.”

References

Pellegrini, Franklin L. (2005) Results of a Large-Scale Necroscopic Study of Equine Colonic Ulcers. J Equine Vet Sci 2005; 25 (3) 113-117.

Cargile JL et al. (2004) Effect of dietary corn oil supplementation on equine gastric fluid acid, sodium, and prostaglandin E2 content before and during pentagastrin infusion. J Vet Intern Med. 2004 Jul-Aug;18(4):545-9.

Rabuffo TS et al.. (2002) Associations between age or sex and prevalence of gastric ulceration in Standardbred racehorses in training.  J Am Vet Med Assoc. 2002 Oct 15;221(8):1156-9. PMID: 12387386

Dionne RM et al. (2003) Gastric ulcers in Standardbred racehorses: prevalence, lesion description, and risk factors. J Vet Intern Med. 2003 Mar-Apr;17(2):218-22.  PMID: 12683624

Lorenzo-Figueras M et al. (2003)  Effects of exercise on gastric volume and pH in the proximal portion of the stomach of horses.  Am J Vet Res  2002 Nov;63(11):1481-7

McClure SR et al. (1999) Prevalence of gastric ulcers in show horses.  J Am Vet Med Assoc. 1999 Oct 15;215(8):1130-3

O’Conner  et al. (2004) Evaluation of urine sucrose concentration for detection of gastric ulcers in horses.  2004 Jan;65(1):31-9.

Sandin A et al.  (1999)  Effects of intramuscular omeprazole on gastric acid secretion in horses over a twenty-four hour period. Equine Vet J Suppl. 1999 Apr;(29):50-3

Murray MJ et al. (1996) Effects of intermittent feed deprivation, intermittent feed deprivation with ranitidine administration, and stall confinement with ad libitum access to hay on gastric ulceration in horses. Equine Vet J Suppl. 1996 Nov;57(11):1599-603

Murray MJ et al. (1989) Gastric ulcers in horses: a comparison of endoscopic findings in horses with and without clinical signs.  Equine Vet J Suppl. 1989 Jun;(7):68-72

Andrews FM et al (2002) Comparison of endoscopic, necropsy and histology scoring of equine gastric ulcers.  Equine Vet J. 2002 Jul;34(5):475-8.

Murray MJ et al. (2001) Histological characteristics of induced acute peptic injury in equine gastric squamous epithelium. Equine Vet J. 2001 Nov;33(6):554-60.

Nieto JE, et al. (2004) Prevalence of gastric ulcers in endurance horses--a preliminary report. Vet J. 2004 Jan;167(1):33-7

Nadeau JA et al. (2000) Evaluation of diet as a cause of gastric ulcers in horses. Am J Vet Res. 2000 Jul;61(7):784-90.

Fleming 2005, see complete study in this issue of EN

(1)

Omeprazole is labelled for use for a maximum of 90 days in horses. We simply have no data on the consequences of long term use in horses. In laboratory species and humans, long term use is associated with hypergastrinemia, rugal hypertrophy and gastric carcinoids (ie, it is not normal not to produce gastric acid chronically). In elderly patients especially, the chronic use of omeprazole has some association with becoming infected with Clostridium difficile (changing the normal environment leading to colonization with a pathogenic bacteria). There has not been sufficient use of omeprazole in a wide variety of horses nor long term use for any of us in veterinary medicine to make any associations like this for horses. It is my opinion that omeprazole is not a perfectly innocuous drug and I would not put horses on it for longer than 90 days without more data.  Trisha Dowling, DVM