Equine Squamous Gastric Disease: Prevalence, Impact and Management

Figures & data

Figure 1 The normal equine stomach showing the four distinct anatomical regions. A, ventral fundus, B, cardia; C, pylorus; D, dorsal fundus. Image adapted with permission of Equine Veterinary Journal. Martineau H, Thompson H, Taylor D. Pathology of gastritis and gastric ulceration in the horse. Part 1: range of lesions present in 21 mature individuals. Equine Vet J. 2009;41(7):638–644.²³

Figure 2 Hyperkeratosis (white arrow). Notice the thickened, corrugated squamous mucosa surrounding the cardia. Regions of hyperkeratosis often have a characteristic yellowish discoloration. Image property of the author.

Figure 3 Parakeratotic hyperkeratosis (dashed arrow). Bar = 400 μm. Image reproduced with permission of Equine Veterinary Journal. Martineau H, Thompson H, Taylor D. Pathology of gastritis and gastric ulceration in the horse. Part 1: range of lesions present in 21 mature individuals. Equine Vet J. 2009;41(7):638–644.²³

Abbreviations: K, keratinized epithelium; NKE, non-keratinized epithelium; LP, lamina propria.

Figure 4 Erosion (white arrow). Notice the focal region of squamous mucosa that is smooth and reddish/pink in appearance. This represents thinning of the squamous epithelium and loss of the keratinized layer. Image courtesy of Henny Martineau.

Figure 5 Erosion (black arrow) adjacent to normal squamous epithelium. Bar = 1000 μm. Notice the dramatic thinning of the affected epithelium. Image reproduced with permission of Equine Veterinary Journal. Martineau H, Thompson H, Taylor D. Pathology of gastritis and gastric ulceration in the horse. Part 1: range of lesions present in 21 mature individuals. Equine Vet J. 2009;41(7):638–644.²³

Abbreviations: E, epithelium; LP, lamina propria; MM, muscularis mucosa; SM, submucosa.

Figure 6 Ulcer (white arrow). Notice the characteristic depressed center surrounded by a prominent margin of tissue. Image property of the author.

Figure 7 Bleeding ulcer (white arrow). Ulcers may be associated with active hemorrhage when severe. Image property of the author.

Figure 8 Ulcer (single black arrow) adjacent to normal squamous epithelium. Notice the complete loss of epithelium in the ulcer bed and exposure of the underlying lamina propria. Prominent epithelial projections can be seen in the normal mucosa immediately adjacent to the ulcer (double black arrows). Bar = 1000 μm. Image reproduced with permission of Equine Veterinary Journal. Martineau H, Thompson H, Taylor D. Pathology of gastritis and gastric ulceration in the horse. Part 1: range of lesions present in 21 mature individuals. Equine Vet J. 2009;41(7):638–644.²³

Abbreviations: E, epithelium; LP, lamina propria; MM, muscularis mucosa; SM, submucosa.

Table 1 Prevalence of ESGD in Different Populations of Horses and Associated Risk Factors

Population	Prevalence	Risk Factors	Limitations	Ref.
Racehorses
TB	52–92% Prevalence 92% in symptomatic horses and 52% in asymptomatic horses	Active training		[^Citation41]
TB	93%	Active racing within the previous 2 months	Small sample size (n=67)	[^Citation53]
TB	82%			[^Citation54]
SB	87%	Horses ≥ 3 years old; geldings		[^Citation59]
SB	44%	Active racing [OR 9.3]; gait - trotters more likely to have ESGD than pacers [OR 2.2]; poor body condition; horses living at racetracks; increasing age		[^Citation39]
TB, SB	86%			[^Citation15]
SB	88%	Intensity of training [OR 6.71]; horses in their first 5 months of training with the highest risk at 3 months [OR 6.17]	Small sample size (n=48); limited to 3 training yards	[^Citation20]
SB	70%	Horses that have raced in the last month [OR 14.7]		[^Citation40]
TB, SB	88%	Horses ≥ 3 years old; no difference in prevalence between horses stabled full time, kept at pasture for part of the day or kept at pasture full time		[^Citation60]
TB	72%	Horses with stereotypies [OR 5]; time in work ≤6 weeks [OR 0.3]; aggression towards to humans [OR 0.12]		[^Citation37]
Endurance horses
Arab, other	57%	Age; final ride position; days a week trained; hours a day trained	Small sample size (n=37)	[^Citation61]
Arab, Anglo-Arab	48–93% Prevalence 48% during the inter-season period and 93% during the competition season	Longer endurance race distance; high starch diet	Small sample size (n=30)	[^Citation42]
Non-racing performance horses
Mixed breeds	58%	Active competition; nervous disposition; lower RBC counts and hemoglobin concentration	Small sample size (n=50)	[^Citation62]
QH Western performance	40%			[^Citation63]
Mixed breeds Dressage, show jumping, western performance, endurance	17–56% Prevalence 17% before competition season and 56% after competition season	Active competition		[^Citation43]
WB Show jumpers	25%	Increased exercise intensity [OR 3.8]	Small sample size (n=83); limited to a small geographical radius	[^Citation38]
TB, other Polo ponies	37%	Decreasing exercise duration [OR 19.5]	Small sample size (n=63)	[^Citation64]
Non-performance horses
American paint horses	Experimental study	Transport and stall confinement		[^Citation47]
Mixed breeds	Experimental study	Repeated administration of oral electrolytes		[^Citation48]
Mixed breeds Riding school	11%	Horses aged 2–6 or 18–23 years old	Small sample size (n=80); limited to one riding centre	[^Citation65]
TB Broodmares	67–76% Prevalence 67% in pregnant mares and 76% in non-pregnant mares		Small sample size (n=62); limited to one breeding farm	[^Citation66]
Mixed breeds Pleasure horses	53%	Straw only available forage [OR 4.2]; ≥ 1 g/kg BW of starch per meal [OR 2.6]; water not available in the turnout paddock [OR 2.3]; interval between forage feeding >6 h [OR 5.3]		[^Citation19, ^Citation46]
Mixed breeds Pleasure horses	48–66 Prevalence 66% in symptomatic horses and 48% in asymptomatic horses			[^Citation67]
Donkeys and wild equids
Donkeys	38%		Small sample size (n=39)	[^Citation68]
Zebras in captivity	64%		Small sample size (n=55); postmortem study - prevalence may have been influenced by concomitant disease	[^Citation69]
Feral horses	22% Prevalence 61% in domestic horses and 22% in feral horses		Abattoir study - prevalence may have been influenced by transport and fasting	[^Citation56]
Foals
TB foals 2–85 days old	47–57% Prevalence 47% in Ireland and 57% in England			[^Citation70]
WB foals 82–200 days old	7–97% Prevalence 7% before weaning and 97% after weaning		Limited to one breeding farm	[^Citation18]
Mixed breeds 1–180 days old	17% Prevalence lowest in neonatal foals	Foals > 1 month old; concomitant gastrointestinal disease	Postmortem study - prevalence may have been influenced by concomitant disease	[^Citation58]

Note: Colors denotes different subpopulations of horses.

Abbreviations: OR, odds ratio; QH, Quarter horse; SB, Standardbred; TB, Thoroughbred; WB, Warmblood.

Table 2 Reported Dose Rates for Oral Omeprazole for the Treatment or Prophylaxis of ESGD

Dose	Formula	Population	Outcome	Limitations	Ref.
1 mg/kg bwt	Gastrogard^® Buffered paste	6 TB horses Experimental	Increased gastric pH Better on low hay diet	Experimental study; small number of horses; outcome measured by change in pH not effect on ulceration	[^Citation95]
4 mg/kg bwt	Gastrogard^® Buffered paste	6 TB horses Experimental	Increased gastric pH Better on low hay diet	Experimental study; small number of horses; outcome measured by change in pH not effect on ulceration	[^Citation95]
4 mg/kg bwt	Gastrogard^® Buffered paste	140 horses and foals	Improved: 99% Healed: 87%	Only re-evaluated at 28 days so response to treatment could have occurred sooner; mixed population; some administration intermittent with racehorse withdrawal times	[^Citation102]
1 mg/kg bwt Pre-exercise	Gastrozol^® Enteric coated paste	18 TB racehorses	Improved: 100% Healed: 89%	Exact period of fasting before medication administered unknown; cannot extrapolate to buffered or plain paste; small number of horses	[^Citation98]
2 mg/kg bwt Pre-exercise	Gastrozol^® Enteric coated paste	16 TB racehorses	Improved: 100% Healed: 94%	Exact period of fasting before medication administered unknown; cannot extrapolate to buffered or plain paste; small number of horses	[^Citation98]
4 mg/kg bwt Pre-exercise	Gastrozol^® Enteric coated paste	16 TB racehorses	Improved: 88% Healed: 75%	Exact period of fasting before medication administered unknown; cannot extrapolate to buffered or plain paste; small number of horses	[^Citation98]
4 mg/kg bwt Pre-exercise	Abgard^® Buffered paste	13 TB race horses in training	Improved: 100% Healed: 92%	Small number of horses	[^Citation107]
4 mg/kg bwt Post-exercise	Abgard^® Buffered paste	12 TB racehorses in training	Improved: 92% Healed: 67%	Small number of horses	[^Citation107]
4 mg/kg bwt	Peptizole ^® Plain paste OR Gastrogard ^® Buffered paste	27 mixed breed horses	Improved 89% Healed 67%	Plain and buffered formulations combined into same category; management not standardized	[^Citation100]
0.5 mg/kg bwt	Gastrozol^® Enteric coated paste	17 TB racehorses in training	Prophylaxis 12% worsened	Small number of horses; limited to racehorse population; cannot extrapolate to buffered or plain paste	[^Citation108]
1 mg/kg bwt	Gastrozol^® Enteric coated paste	16 TB racehorses in training	Prophylaxis 6% worsened	Small number of horses; limited to racehorse population; cannot extrapolate to buffered or plain paste	[^Citation108]

Note: Colors denote different studies.

Abbreviations: bwt, body weight; TB, Thoroughbred.

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