Gastric Ulceration - Horse

Also known as:

Gastroduodenal ulceration Equine Gastric Ulcer Syndrome Equine Gastric Ulcer

Prevalence

Racehorses 80-100% (Hammond et al 1986, Vatistas et al 1994 and 1997, Murray et al 1996) Show horses 60% (McClure et al 1999) Ponies 78% (MacAllister et al 1982) Endurance 67% (Pieto et al 2004)

Signalment

Foals and young horses in training

Pathophysiology

NOT associated with Helicobacter pylori and not typically associated with Gasterophilus

Risk Factors

Housing, stress, boredom, training, diet Feeding practices:

• Grain and pelleted feed asssociated with increased serum gastrin (Smyth et al 1988)
• Eating behaviour (grazing vs feeds)
• Feed constituents (alfalfa)
• Individual variability

Exercise and training

• Strenuous exercise stimulates gastrin release which has effects on HCL secretion, gastric emptying, gastric blood flow

Clinical syndrome

Often asymptomatic, may see:

• Poor appetite
• Dullness
• Change in attitude
• Reduced performance
• Reluctance to train
• Poor condition
• Weight loss
• Diarrhoea
• Low-grade colic
• Excessive recumbency
• Bruxism (in foals only and almost pathognomonic)

Diagnosis

Definitive diagnosis requires gastroscopy (cannot do in foals as need to starve prior to exam)

Laboratory tests

No known laboratory markers, attempts to detect occult blood in faeces unreliable in horse

Endoscopy

EGUS Lesion Scoring System (2 in Sanchez)

|} |Lesion Grade |Description |- |Grade 0 |Intact epithelium with no appearance of hyperaemia or hyperkeratosis |- |Grade 1 |Intact mucosa with areas of reddening or hyperkeratosis (squamous) |- |Grade 2 |Small single of multifocal lesions |- |Grade 3 |Large single or multifocal lesions or extensive superficial lesions |- |Grade 4 |Extensive lesions with areas of deep ulceration |}

Minimum endoscope length of two metres and 2.8-3.0 metre instruments are reuired for duodenoscopy Foals - lesions mainly in glandular epithelium Adults - margo plicatus and squamous epithelium

Treatment

Proton pump inhibitors: only omeprazole (Gastroguard) is licensed for horses. Given PO once daily (4mg/kg) for 3-4 wks, most effective drug at controlling HCl secretion (decreases basal and stimulated release). Expensive and not absorbed in foas with diarrhoea Histamine H2 receptor antagonists:

• ranitidine 7mg/kg TID for 3-4wks
• cimetidine 25mg/kg QID for 3-4wks (cheaper but less effective so must be given more frequently)

Gastric protectants: sucralfate 10-20mg/kg TID for 2-4wks Antacids: magnesium and aluminium hydroxides (NOT recommended as have massive rebound effect)

Prognosis

Complications:

• Recurrence if management not altered
• Perforation and peritonitis (rare - foals)
• Pyloric stenosis (rare - foals)

Prevention

Gastroguard at lower dose (1-2mg/kg) daily for 3-4wks (100, 107-109 in Sanchez) Prophylaxis in foals controversial as gastric acidity may be protective against bacterial translocation (Sanchez). It may be beneficial in foals receiving substantial doses of NSAIDs for orthopaedic pain (Sanchez) Management: diet, training, exercise, stress (company, toys) Pasture turnout and continuous access to high quality forage especially alfalfa (Sanchez)

References

Gastric Ulceration - all species

• Affects the pars oesophagea (margo plicatus) in adults and foals.
• Due to parasites - Gasterophilus (Bots).
• Bots are not as common as they once were.
• Look like big pink maggots.
• Killed by Ivermectin.
• Gasterophilus leave large ulcers in glandular regions of the stomach.
  • Ulcers / erosions are quite deep.
• The parasites are believed to be non-pathogenic, but in large numbers they probably produce some discomfort and poor growth.
• Carcinoma can also produce ulceration in the stomach of the horse as, in other species.

• In foals, the glandular area may sometimes be affected.
  • This may be e.g. stress-related, or due to used of NSAIDs.