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Stomach Ulcers/Equine Gastric Ulcer Syndrome (EGUS) In Horses FAQ's

I have been told that my horse may have the stomach ulcers. How did he get these ulcers, and how should I treat them?

Is there more than one type of ulcers?

How long does it take for ulcers to develop?

Do all performance horses have ulcers?

How are ulcers diagnosed?

What are the clinical signs of Equine Gastric Ulcer Syndrome (EGUS)?

What are the common therapies for Ulcers/EGUS?

What are the risk factors for a horse to get ulcers?

What management strategies can I use to help decrease or prevent ulcers in my horses?

What kind of hay is best to feed a horse with a history of ulcers?

Ulcer References

Question: I have been told that my horse may have the stomach ulcers. How did he get these ulcers, and how should I treat them?

Answer: Horses get stomach ulcers just like people get stomach ulcers. Generally speaking stomach ulcers are primarily due to stress. Specific reasons include: stressful transport, prolonged stall rest, general management issues, infrequent feeding and use of certain medications over a prolonged period of time. Medications specifically include nonsteroidal anti-inflammatory medications such as "Bute" and Banamine. Also high on the list is dexamethasone.

Recent studies have shown a surprisingly high proportion of horses suffer from stomach ulcers. Symptoms of stomach ulcers in horses can vary depending upon the severity of the ulcers. Severe ulcers may often cause colic or diarrhea. Moderate ulcers may manifest as weight loss, or general "dullness". Mild ulcers may only present as poor performance (reluctant to jump, or a bad attitude).

There are several medications available for treatment of stomach ulcers in horses. The treatment of choice is Gastrogard paste. Gastrogard works by inhibiting secretion of stomach acid. (note: "Generic gastrogard" products are poorly absorbed by horses) Gastrogard is an excellent product. In fact, I often recommend gastrogard for USET horses when traveling over 8 hours. The horses usually drink more en route, and arrive in much better shape than they would otherwise.

Stomach buffer type products are also used widely. These can be effective for long-term management of horses. However, stomach buffers are generally not very effective at healing stomach ulcers!! Nonetheless, many horses will improve their performance during competition season if they are treated with a daily stomach buffer.

The best way to diagnose stomach ulcers is by using a fiber-optic endoscope, ("gastroscope") to actually visualize the inside of the stomach. By doing so, one confirms the diagnosis as well as evaluating the degree of severity. This technique requires an especially long endoscope. An alternative may involve a trial use of an anti-ulcer medication for 7 to 14 days. If the horse responds favorably, it may be suggestive of stomach ulceration. Most insurance companies require gastroscopy for a definitive diagnosis of gastric ulceration.

Finally and most importantly, I recommend revisiting your management scenario if your horse has stomach ulcers. Most horses with ulcers will do better with more pasture turnout, more frequent meals, and some friendly neighbors. There are many variations on these themes, so you need to treat each case as an individual. Be sure to minimize anti-inflammatory medications. It is worth scrutinizing your program, because even after "completely healing ulcers", they can and recur within 72 hours if the underlying problems are not addressed.

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Question:   Are there more than one type of ulcers?

Answer:   In adult horses there are two main types of stomach ulcers, ulcers in the glandular portion of the stomach, and ulcers in the non-glandular or squamous mucosa portion of the stomach. The first type is often related to non-steroidal anti-inflammatory (NSAID) therapy with products such as phenylbutazone (bute) or flunixin meglumine (banamine) (Picavet, 2002). Other contributing factors include concurrent illness, pain, or physiological stress. This type of ulcer less commonly can occur spontaneously as well with or without ulcers of the non-glandular portion of the stomach (Hinchcliff, et al, 2004). The non-glandular region ulcers are the kind most often encountered in adult and performance horses (Robinson, 2003).

      In either case, an ulcer results from an imbalance between acid production in the stomach, and the protective factors produced by the body to protect the stomach lining from this acid. Prolonged NSAID therapy for instance suppresses a hormone, Prostaglandin E2 (PGE2) that stimulates production of bicarbonate, mucus, and proteins as well as increasing blood flow to the stomach which are all protective factors against acid. The more common form of ulcers in sport horses, tends to occur due to an over production of acid, or increased exposure to the stomach lining to the acid produced. Sympathetic nervous system stimulation which occurs when a horse experiences stress similarly acts to decrease bicarbonate production and maintain a more acidic pH in the stomach (Flemstrom, 2001). One of the body's natural responses to stress is to release a compound called ACTH which has a decreasing effect on PGE2 as well.

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Question:   How long does it take for ulcers to develop?

Answer:   A recent study (McClure et al, 2005a) noted that activities that are typical in show/training environment were ulcerogenic and can result in the development of ulcers in as little as 5 days.

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Question:   Do all performance horses have ulcers?

Answer:    Various studies have reported the incidence of ulcers in performance horses to range from 40-60% in sport horses such as dressage, show jumping (McClure et al. 1999, Mitchell 2001), endurance (Nieto et al. 2004), and western performance (Bertone, 2000) while the incidence in race horses is reported to be as high as 80-90% (Murray, 1996-2000 and Vatistas, 1999).

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Question:   How are ulcers diagnosed?

Answer:   Due to the relatively non-specific and vague nature of most of the clinical signs of ulcers, only a presumptive diagnosis can be made based on the clinical signs. For a definitive diagnosis endoscopic examination or positive response to ulcer therapy is required. The correlation of the number and severity of ulcers found during endoscopic examination does not always coincide with the severity of the clinical signs (Hinchcliff et al, 2004).   A positive response to therapy with H2 Antagonist, or Proton Pump Inhibitors is often used to diagnose the presence of ulcers in horses presenting vague clinical signs such as decreased appetite, intermittent diarrhea, and poor performance that are experiencing environmental stressors.

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Question:   What are the clinical signs of Equine Gastric Ulcer Syndrome (EGUS)?

Answer:   The clinical signs of EGUS vary significantly with the severity of the ulcerative lesion and the location of the lesion. Glandular stomach ulcers are often associated with overt clinical signs such as colic after eating and decreased appetite (Hinchcliff et al, 2004). Either type of ulcer may present one or more of the following signs:

        -     acute and recurring colic, often following eating

      -      increased recumbency (lying down) or even lying on their back to relieve abdominal pain

      -      poor body condition, difficult to keep at appropriate weight

      -      poor hair coat

      -      taking a long time to eat the concentrate portion of their feed

      -      preferring to eat hay versus grain

      -      decreased appetite

      -      intermittent chronic diarrhea

      -      unexplained poor performance

      -      attitude changes (i.e. aggressive or nervous, or depressed)

      -      behavior changes (grinding teeth, excessive salivation)

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Question:   What are the common therapies for Ulcers/EGUS?

Answer:   Traditionally antacids were used to decrease the discomfort and increase the pH of the stomach contents. The traditional components are usually a combination of magnesium hydroxide and aluminum hydroxide (i.e. Neighlox). The effect of even a large dose (240-360 ml) of these compounds is short lived and would require repeat dosing every 2-6 hours to have any real effect on ulcer healing (Hinchcliff et al, 2004). Additionally these compounds can reduce the absorbability of some other medications given orally. Bismuth compounds, such as Pepto Bismol have not been shown to have any significant effect at all (Picavet, 2002). Various other remedies (i.e. Papaya, Gastrex) have been used as antacid therapy in horses with variable results.

      Coating agents such as Sucralfate (dose range from 10-40 mg/kg) also require frequent dosing (every 6-8 hrs) to have an effect. The act by forming a protective gel-like coating over the ulcers themselves, and therefore have no direct healing effect (Robinson, 2003). They are most effective when used in combination with H2 Antagonist drugs (Hinchcliff et al, 2004).

      H2 (Histamine receptor) Antagonist drugs act to suppress acid secretion without completely blocking acid production. This class includes drugs such as Cimetidine (15-25 mg/kg), and Ranitidine (6.6 mg/kg) both of which require dosing 4 times per day (every 8 hours) to be effective (Merritt, 2003; Hinchcliff et al, 2004; Robinson, 2003).

      Proton Pump inhibitors such as omeprazole paste (Trade Name GastroGard) block the secretion of acid for up to 27 hours at the full dose (Robinson, 2003), therefore making administration of the medication easier to manage. An Australian study found that omeprazole was more effective at healing ulcers than ranitidine with noticeable improvement after 14 days of therapy and lasting benefit greater than 28 days after the therapy (Lester et al, 2005). Recommended dosage of GastroGard is 1 tube per 1000 lb horse per day (4 mg/kg every 24 hours) to promote healing and prevent recurrence of ulcers. A dosage of ½ tube for a 1000 lb horse per day (2 mg/kg every 24 hours) following 28 days of full dose therapy has been shown to prevent recurrence of ulcers (Andrews, 1999).   Studies performed in race horses in training, found that a dose of GastroGard paste at ¼ tube per 1000 lb horse per day (1 mg/kg every 24 hours) was effective in both preventing ulcers in horses starting race training (Andrews, 1999; McClure et al, 2005b; White et al, 2003), and in preventing the recurrence of ulcers in horses in race training (McClure et al, 2005c; White et al, 2003).

      GastroGard was formulated and manufactured following extensive research to create a unique drug for horses. Although the active ingredient, omeprazole, is used widely in humans, the molecular structure was modified specifically for extended absorption in horses. Therefore, the use of the human formulations of omeprazole may be less effective and require more frequent administration.

      Merial, the makers of GastroGard, have now formulated a non-prescription form of the drug omeprazole (1mg/kg dose label) called UlcerGard. Non-prescription medications are not subjected to the same stringent research and quality control procedures as prescription formulations, which is why the non-prescription form can be marketed at a significantly lower cost.

      In summary, the recommended dose of GastroGard (the only FDA approved formulation of omeprazole for horses currently) depends on a number of factors such as whether non-healed ulcers are present, whether ulcers were present, but have healed, or whether there are currently no ulcers at all as well as the "stress" the horse in question is being subjected to currently. In general to heal ulcers requires a dose of 1 tube per 1000 lb horse per day (4mg/kg/day) for at least one month. Maintenance or preventative therapy with GastroGard in horses that have ulcers that have healed may only require ¼ to ½ tube per 1000 lb horse per day (1-2 mg/kg/day). Therapeutic dosage is dependent on all of the above factors including the degree of ulceration present, management and the individual horse in question.

      In some horse with chronic EGUS which is not responsive to traditional therapy, a bacterial component may be contributing to the syndrome. A combination therapy of 1 tube per 1000 lb horse per day omeprazole paste (4 mg/kg every 24 hrs), metronidazole (15 mg/kg orally every 6-8 hrs) or SMZ's (15-25 mg/kg orally every 12 hrs), and bismuth subsalicylate (3.8 mg/kg every 6 hrs) for a period of 14 days may be effective (Andrews FM,2005).

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Question:   What are the risk factors for a horse to get ulcers?

Answer:    -   concurrent illness or pain

               -   food deprivation

               -   strenuous exercise

               -   stall confinement

               -   changes in management (i.e. trailering, new environment, change in daily routine)

               -   diets high in fermentable carbohydrates (high concentrate portion) can produce volatile fatty acids which under prolonged exposure to acid or low pH can damage the stomach lining

               -   prolonged NSAID therapy

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Question:   What management strategies can I use to help decrease or prevent ulcers in my horses?

Answer:   Management therapies that have been recommend to aid in treating and preventing EGUS include:       

      -   allowing turnout and avoiding stall confinement to decrease environmental stress

      -   feeding free choice hay (either alfalfa or high quality grass hay)

      -   limit high soluble carbohydrate concentrates

      -   feed a complete pelleted feed with concentrate and roughage in one

      -   avoid food deprivation, limit fasting periods

      -   top dress feed with corn oil or linoleic acid supplement (these provide the precursors of PGE2 which in turn acts to stimulate production of protective factors for the stomach lining).

      -   avoid prolonged NSAID therapy

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Question:   What kind of hay is best to feed a horse with a history of ulcers?

Answer:   The pattern of hay feeding is more important than the type. Free choice feeding of hay helps maintain the pH of the stomach environment at a level less likely to promote ulcer formation. There have been studies that show alfalfa hay to have a more beneficial effect compared to grass hay. This may be due to the higher calcium and protein content of alfalfa hay (Robinson, 2003).

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Andrews FM, Sifferman RL, Bernard W, et al. Efficacy of omeprazole paste in the treatment and prevention of gastric ulcers in horses. Equine Vet J Suppl 1999; 29:81-86.

Andrews FM. Ulcers in the Stomach and Colon; Diagnosis and Treatment: A Pain in the Gut! Proceedings Am Assoc Equine Pract Focus Meeting 2005.

Bertone JJ. Prevalence of gastric ulcers in elite, heavy use western performance horses. Proceedings Am Assoc Equine Pract 2000; 46:256-259.

Flemstrom G. Isenberg JI. Gastroduodenal mucosal alkaline secretion and mucosal protection. News Physiol Sci 2001; 16:23-28

Hinchcliff KW, Kaneps AJ, Geor RJ eds. Gastro Intestinal Disease of performance horses by Guy D. Lester in Equine Sports Medicine and Surgery , 2004. 48:1037-1048.

Lester GD, Smith RL, Robertson CD. Effects of treatment with omeprazole or ranitidine on gastric squamous ulceration in racing Thoroughbreds. J Am Vet Med Assoc 2005; 227:1636-1639.

McClure, S.; Carithers D., Gross, S.; Murray, M. Gastric ulcer development in horses in simulated show or training environment. J Am Vet Med Assoc 2005; 227:775-777.

McClure SR, et al. Efficacy of omeprazole paste for prevention of gastric ulcers in horses in race training. J Am Vet Med Assoc 2005; 226:1681-1684.

McClure SR, et al. Efficacy of omeprazole paste for prevention of recurrence of gastric ulcers in horses in race training. J Am Vet Med Assoc 2005; 226:1685-1688.

McClure, SR; Glickman LT, Glickman NW. Prevalence of gastric ulcers in show horses. J Am Vet Med Assoc 1999; 215:1130-1133.

Merritt AM. Equine Gastric Ulcer Syndrome (EGUS): Anti-Ulcer Therapy. 8 th Congress on Equine Medicine and Surgery ; Dec, 2003.

Mitchell, RD. Prevalence of gastric ulcers in hunter/jumper and dressage horses evaluated for poor performance. In: Proceedings of the 21 st Ann Conf Assoc Equine Sports Med, September 2001.

Murray MJ, Nout YS, Ward DL. Endoscopic findings of the gastric antrum and pylorus in horses: 162 cases (1996-2000). J Vet Intern Med 2001; 15:401-406.

Nieto, JE, Snyder, JR, Beldomenico, P, et al. Prevalence of gastric ulcers in endurance horses - a preliminary report. Vet J 2004; 167:33-37.

Robinson, NE. Current Therapy in Equine Medicine 5. 2003. Gastric Ulcer Syndrome 3.4: 94-98.

Vatistas NJ, Snyder JR, Carlson G, et al. Cross-sectional study of gastric ulcers of the squamous mucosa in thoroughbred racehorse. Equine Vet J Suppl 1999; 34-39.

White GW, et al. Prevention of Occurrence and Recurrence of Gastric Ulcers in Horses by Treatment with Omeprazole at 1 mg/kg/day. Proceedings Am Assoc Equine Pract 2003; 49:220-221.

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