1. Diseases of the Stomach
Frank M. Andrews, DVM, MS, DACVIM
Professor of LA Medicine
The University of Tennessee, CVM

2. Equine Gastric Ulcer Syndrome
Photo courtesy of MJ Murray.

3. Prevalence of Equine Gastric Ulcer Syndrome (EGUS)
60% to 93% in performance horses
25% to 50% in foals
Murray et al, Equine Vet J, 1996; Murray, JAVMA, 1989; Murray, AAEP, 1997.

4. EGUS: Public Perceptions
Telephone Survey conducted in 2003, of 300 performance horse owners

5. Impact of EGUS on Adult Horses
Results in poor body condition
Can disrupt training
Can impair performance
Can cause colic
Can have severe complications
duodenal strictures
Murray, AAEP, 1997; Murray, Vet Med, 1991.

6. Photos courtesy of MJ Murray.
Impact of EGUS on Foals
Gastric outflow obstruction
Esophagitis
Chronic ulceration
Perforation (rupture) & peritonitis
Photos courtesy of MJ Murray.

7. The Stomach of the Horse
Nonglandular region
(squamous epithelium)
Esophagus
Duodenum
Margo plicatus
Pylorus
Glandular region
(glandular epithelium)

8. Compartments of the Equine Stomach
Squamous (nonglandular) tissue. Less resistant to acid injury. 80% of equine ulcers
Glandular & mucus-secreting tissue. More resistant to acid injury. 20% of equine ulcers
Pagan, World Equine Vet Rev, 1997.

9. Cause of EGUS: Aggressive Factors Overpowering Defensive Factors
Gastric lining damage occurs when:
Aggressive (acid, pepsin, bile, organic acids) factors overpower
Defenses (bicarbonate, mucus) of gastric mucosa
Squamous mucosa lining lacks these defenses SM MP GM
Murray, Equine Vet J Suppl, 1992; Sweeney, In Practice, 1992; Pagan, World Equine Vet Rev, 1997; Murray and Schusser, Equine Vet J, 1993.

10. Risk Factors for EGUS: Training/Racing
Intensive exercise
Reduced blood flow to the stomach lining?
Increased gastric acidity?
Altered eating behavior?
March 25
June 3

11. Acids forced into the proximal stomach
Increased intra-abdominal presssure during intense exercise causes
gastric compression, pushing acid contents into proximal stomach
HCl,VFAs
Bile acids
Lorenzo-Figueras and Merritt, AJVR 2002;63:

12. Risk Factors for EGUS: Feeding
Feeding management
Low prevalence of ulcers in horses at pasture
Murray et al, Equine Vet J, 1996.

13. Risk Factors for EGUS: Feeding
Decreased acid when roughage available
Increased serum gastrin when fed concentrates (grains & sweet feeds)
Intermittent feed deprivation = gastric ulcers
Stall confinement = gastric ulcers
Feeding alfalfa hay may help!

14. Gastric Acidity Profile: No Feed
24-Hr Gastric pH: Feed Withheld 7 6 5 4 pH 3 2 1 6 12 18 24
Time (hours)
Murray and Schusser, Equine Vet J, 1993.

15. Gastric Acidity Profile: Grass Hay
24-Hr Gastric pH: Free Choice Hay 8 7 6 5 4 pH 3 2 1 6 12 18 24
Time (hours)
Murray and Schusser, Equine Vet J, 1993.

16. Hydrochloric Acid-Induced Ulcers
Gastric acidity is high in empty stomach
Intermittent feed deprivation
Lesions form in squamous mucosa
No lesions form in glandular mucosa
Lesions prevented by ranitidine (Zantac®)
Day 0
48 hours
96 hours
Murray and Schusser, Equine Vet J, 1993; Murray and Eichorn, Am J Vet Res, 1996.

17. Risk Factors for EGUS: Stress
Physical stress
Illness
Painful musculoskeletal disorder
Behavioral stress
Stall confinement
Transport
Unfamiliar environment, social regrouping

18. Risk Factors for EGUS: Non-Steroidal Anti-Inflammatory Drugs
Phenylbutazone & Flunixin Meglumine and other NSAIDs
Associated with ulcers throughout the intestinal tract (Cecum & Colon)
Inhibit prostaglandins, interrupting mucosal blood flow and mucus
Local toxicity
Murray, Vet Med, 1991.

19. Clinical Signs of EGUS in Adult Horses
Poor appetite
Poor body condition
Attitude changes
Decrease in performance
Mild to moderate colic
Murray, AAEP, 1997.

20. Clinical Signs of EGUS in Foals
Poor appetite or intermittent nursing
Colic
Poor body condition
Frequently lies on back
Bruxism (grinding of teeth)
Excessive salivation (Ptylism)
Diarrhea
Murray, Vet Med, 1991.

22. How can you tell that a Horse has EGUS? (Diagnosis)
Clinical signs are suggestive of, but not specific for, EGUS
Lab: Mild anemia
Response to treatment can be useful
Gastric endoscopy is only definitive diagnostic tool

23. Endoscopic Evaluation
Endoscope quality & dimensions
9 ft long
Small diameter
Patient preparation
Experience
Murray, Vet Med, 1991.

24. Endoscopic Evaluation: Adults
Squamous erosions
fundus
Squamous ulcer
margo plicatus
Squamous ulcers
lesser curvature
Murray (personal communication), Photos courtesy of MJ Murray.

25. Endoscopic Evaluation: Adults (cont’d)
Glandular ulcer
rugal fold
Erosion, hyperplasia
antrum rugal fold
Pyloric ulcer
Murray (personal communication), Photos courtesy of MJ Murray.

26. Endoscopic Evaluation: Foals
Squamous erosion,
desquamation
3 days old
Squamous erosions
30 days old
Bleeding squamous
ulcers
3 months old
Murray (personal communication), Photos courtesy of MJ Murray.

27. Endoscopic Evaluation: Foals (cont’d)
Glandular corpus
ulcers
14 days old
2 months old
Antrum ulcers
3 months old
Pyloric ulcers
Murray (personal communication), Photos courtesy of MJ Murray.

28. Treatment of EGUS Eliminate clinical signs Promote healing
Prevent complications
Prevent recurrences
MacAllister, Vet Med,

29. There Are Two Compatible Approaches to Treatment
Management modifications
Medical therapy-approaches that have been used
Control gastric acid
Mucosal protectants
Murray, AAEP, 1997; MacAllister, Vet Med, 1995.

30. Traditional Management Modifications
Reduce level of training

31. Traditional Management Modifications
Diet modifications
Limit periods of fasting
Increase roughage
pasture turnout (green grass)
free choice hay
Alfalfa hay-dietary antacid
Reduce grain/concentrates
Seahorn, LSU Equine Vet Res Program Newsletter, 1998; Pagan, World Equine Vet Rev, 1997.

32. Dietary Management Fresh Rice Bran and Rice Bran Oil
Contains surface active phospholipids and cytoprotective factors that maintain health of the stomach lining
Rancidity can be a problem
Produces ketoaldehydes which are ulcerogenic
Steam pasteurization can help decrease potential for rancidity
Storage in refrigerator

33. Management Modifications
Limit stressful events
Long-term stall confinement
Trailering
Overcrowding

34. Organic Acids (VFAs or SCFAs) High Concentrate Diets
Acetic, Butyric, Propionic, and Valeric Acids
Byproducts of carbohydrate fermentation in the stomach
Synergistic with HCl
May lead to non-glandular ulcers
Increased VFA’s with increased grain

35. Medical Management of EGUS
Neutralizing agents
Antacids
Antisecretory agents
Histamine H2 receptor antagonists
Prostaglandin analog
Acid pump inhibitors
Others (antibiotics, neutriceuticals)
MacAllister, Vet Med, 1995.

36. Route of administration
Commonly used Anti-Ulcer Medications, Routes, & Doses
Drug
Dosage (mg/kg BWT)
Dosing
interval
Route of administration
Ranitidine*
6.6
Q 6-8 h PO
Ranitidine
1.5
Q 6 h
i.v., i.m.
Cimetidine
20-25
Omeprazole **(GastroGard) 4
Q 24 h
Omeprazole
0.5
i.v.
Sucralphate
20-40
Q 8 h
Al/MgOH antacids
0.5 to 1.0 ml/kg
Q 4-6 h
**GastroGard, Merial LTD, Atlanta, GA. Only Drug Approved for horses

37. GASTROGARD® (Omeprazole)
New oral-paste formulation of omeprazole developed specifically for horses
Well-studied, effective, and safe therapy for EGUS
Approved for use in horses, March 1999

38. Ulcer Treatments Act at Different Sites
Site of Action
H2 antagonists
H2 (+)
ACh (+)
Gastrin (+)
Prostaglandins (-)
PARIETAL CELL
GASTROGARD™
ACID PUMP H+ H+
Sucralfate
MUCUS/BICARBONATE BARRIER H+ H+ H+
CI-
CI-
CI- H+
H+CI-
STOMACH LUMEN
Antacids

39. GastroGard® Allows Healing/Improvement of Ulcers
Sham Dosed (n = 25)
69/75 (92%)
100
GASTROGARD (n = 75)
58/75
(77%) 75
Percent (%) 50
8/25 (32%) 25
1/25
(4%)
Improved
Healed
Freedom of Information (FOI) Summary for GASTROGARD Oral Paste for Equine Ulcers; Andrews et al, Equine Vet J Suppl, 1999.

40. GastroGard® Advantages
Profound gastric acid suppression
Prolonged duration of action
Once-daily dosing
Well studied in horses
No reported treatment-related
health problems in equine trials
Prevents ulcer recurrence
Can maintain training program
Approved for use in horses (GASTROGARD®)
Andrews et al, Comp Cont Educ Pract Bet, 1996.

41. GastroGard®: Disadvantages
No IV formulation available in US
Andrews et al, Comp Cont Educ Pract Bet, 1996.

42. UlcerGard Prevention of ulcers
Non-perscription strength of Gastrogard
Sold through veterinarians

43. Histamine H2 Receptor Antagonists
Zantac® (ranitidine), Tagamet® (cimetidine)
Competitive inhibition of the interaction of histamine with parietal cell
Dose-dependent inhibition of gastric acid secretion
MacAllister, Vet Med, 1995.

44. Histamine H2 Receptor Antagonists: Advantages & Disadvantages
Availability
Low cost (generic)
Zantac® has been shown to significantly inhibit gastric acid secretion in horses
Must be administered 3X daily
Murray, AAEP, 1997.

45. Antibiotic Treatment
Amoxicillin, metronidazole, clarithromycin, bismuth compounds, etc.
Primarily used in humans with Helicobacter pylori
H. pylori has been associated with the stomach of horses, but not EGUS
Antimicrobials may be used in horses with resistant EGUS

46. Recent Studies on Helicobacter spp.
Helicobacter specific DNA isolated from horse stomachs
2 horses with squamous erosions
1 horse with glandular erosions
ACVIM Forum-Dallas (May 2002)
Scott DR, Marcus EA, Shirazi-Beechey SSP, et al. Evidence of Helicobacter infection in the horse. Proc Am Soc Microbiology 2001.

47. Feed Supplements (Neutriceuticals)
NeighLox® (Kentucky Performance Products)
Antacid and Coating Agents:
Aluminum Phosphate, Calcium Carbonate
Dihydroxy-Aluminium Sodium Carbonate
Labeled for prevention of heartburn
No studies in horses to prove or disprove
Probably does not cause any harm

48. Feed Supplements (Neutriceuticals)
G.U.T (Uckele Health & Nutrition)
Gastric ulcer transnutrient for horses with ulcers
Ingredients
Gelatin
Lactobacillus acidophilus, L. lactis
Feed 15 grams (1 scoop) twice daily in horses with ulcers
No studies proving efficacy

49. Feed Supplements (Neutriceuticals)
TractGard (Foxden Equine)
Equine GI rehydrator, antacid, digestaid, and electrolyte salt
Ingredients (1 to 2 scoops daily)
Calcium carbonate, Sodium sequiscarbonate, KCl, MgSO4, distiller’s grain, yeast, and linseed meal
No studies on efficacy

50. Compounded & Generic Omeprazole: Beware!!

51. Conclusions- General EGUS is a major cause of illness
60-93% of performance horses have EGUS
Impacts health, performance, economics
Occurs when aggressive factors overpower gastric defenses

52. Conclusions- General Diagnosis requires endoscopy
Presumptive diagnosis made based on clinical signs following complete diagnostic evaluation
Treatment: management and medical interventions

53. Conclusions- Treatment
Zantac®-healing 3X daily treatment
Dietary supplements-not tested
GastroGard® (omeprazole)
Only FDA approved treatment
Provides potent, long-lasting gastric acid suppression in horses (once daily administration)
92% to 99% improvement in ulcer scores in trials and a wide safety margin
UlcerGard Prevention of Ulcers

54. Duodenal Ulcers/Stricture
Part of EGUS (more commonly in foals)
Similar pathogenesis
Similar clinical signs
Usually associated with bruxism, ptylism, and diarrhea (occurs most often in foals)
Delayed gastric emptying
Associated with esophageal
ulcers

55. Duodenal Ulcers/Strictures
Diagnosis
Clinical signs
Duodenoscopy
Radiology
gastric emptying with barium swallows (liquid meal=30 minutes)
Necropsy

56. Duodenal Ulcers/Strictures
Treatment
Omeprazole (4 mg/kg, PO, Q24h, 28 days)
Omeprazole (0.5 mg/kg, IV, Q24h)
Ranitidine (6.6 mg/kg, PO, Q8h)
Surgery-Gastrojejunostomy (foals only?)

57. Gastric Neoplasia Uncommon in older horses
Squamous cell carcinoma, most common
Others: lymphosarcoma, adenosarcoma
Arises from squamous mucosa and metastasizes to the abdominal cavity and viscera and/or extends up the esophagus
Clinical signs:
Chronic weight loss
Anemia
Naso-gastric reflux
Colic

58. Gastric Neoplasia Diagnosis Clinical Signs Endoscopy (definitive)
Abdominal ultrasound
Necropsy
Treatment: None
Prognosis: Grave

59. Gastric Impaction Infrequent cause of Colic in horses
Dry feed material and decreased water intake
May occur during winter when dry hay is fed and water intake is lower
Diagnosed at surgery in horses with colic
Endoscopic examination
Treatment with dioctyl sodium succinate (DSS)
5% solution via NG tube in 4 to 6 L fluid
Lavage at surgery, resolve in 24 – 48 hours