Equine Gastric Ulcers

Gastric ulceration is a serious yet common condition that can affect any horse – from the most sedate pony to performance and racehorses.

Non-performance, performance and racehorses

Studies indicate that gastric ulcers occur in up to:

37% of leisure horses¹
63% of performance horses^2,3
93% of racehorses⁴

Foals are also at particular risk - around 50% of foals develop stomach ulcers, particularly in the first few months of life⁵.

Risk factors
All the risk factors for equine gastric ulcers have yet to be determined, but some of the more commonly encountered ones are presented below. It is important to note, however, that horses can develop severe ulcers even in the absence of these characteristic risk factors^1,5.

Diet
As horses are ‘trickle feeders’ there is a continuous secretion of acid within the stomach, so prolonged periods without food to neutralise that acid can lead to ulceration. When horses are denied free access to feed or fail to eat, ulcers develop rapidly⁸. Use of concentrated feeds may also contribute to ulcer risk by reducing the time spent feeding and increasing gastrin levels⁹.

Intensive exercise
There is a definite association between equine training and gastric ulceration. Even non-intensive training is associated with a high prevalence of stomach ulcers². It has been shown that blood flow to the stomach (which helps to remove acid) decreases with exercise⁶ - while increased pressure in the abdomen during exercise pushes acid up into the sensitive portion of the stomach⁷.

Physical stress and illness
Gastric ulcers can occur in response to physiological stress. Shock, respiratory disease and traumatic injury may play a role. Equine transportation¹⁰ and stable confinement⁸ are proven risk factors in causing ulcers.

Psychological stress
While psychological stress is difficult to evaluate in horses and foals, stressful conditions may adversely influence feed intake, resulting in periods of increased stomach acidity¹¹.

Medication
Some long-term medications can produce adverse gastric effects, as they may inhibit production of the substances that help to protect the stomach¹².


	*References*
	1.	Murray MJ, Grodinsky C, Anderson CW, Radue PF et al. Gastric ulcers in horses: A comparison of endoscopic findings in horses with and without clinical signs. Equine Vet J 1989; 7 (suppl): 68-72.
	2.	Mitchell RD. Prevalence of gastric ulcers in hunter/jumper and dressage horses evaluated for poor performance. In: Proceedings of the Association of Equine Sports Medicine Annual Meeting 2001.
	3.	Nieto JE, Snyder JR, Beldomenico P, Aleman M, Kerr JW, Spier SJ. Prevalence of gastric ulcers in endurance horses - a preliminary report. Vet J 2004 Jan; 167 (1): 33-37.
	4.	Murray MJ et al. Factors associated with gastric lesions in Throughbred racehorses. Equine Vet J 1996; 25 (5): 368-374.
	5.	Murray MJ et al. Prevalence of gastric disease: an endoscopic survey. Equine Vet J 1990; 22(1): 6-8.
	6.	Manohar M, Goetz TE, Saupe B, Hutchens E, Coney E. Thyroid, renal and splanchnic circulation in horses at rest and during short-term exercise. Am J Vet Res 1995; 56: 1356-1361.
	7.	Lorenzo-Figueras M et al. Effects of execise on gastric volume and pH in the proximal portion of the stomach of horses. AVJR 2002; 63(11): 1481-1487.
	8.	Murray MJ, Eichorn ES. 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. Am J Vet Res 1996; 57: 1599-1603.
	9.	Smyth GB, Young DW, Hammond LS. Effects of diet and feeding on postprandial serum gastrin and insulin concentration in adult horses. Equine Vet J 1989: 7(suppl): 56-59.
	10.	McClure SR et al. Gastric ulcer development in horses in a simulated show or training enviroment. JAVMA 2005; Vol 227 (5): 775-777.
	11.	Furr MO, Murray MJ, Ferguson DC. The effects of stress on gastric ulceration, T3, T4, reverse T3 and cortisol in neonatal foals. Equine Vet J 1992; 24:37-40.
	12.	MacAllister CG, Morgan SJ, Borne AT et al. Comparison of adverse effects of phenylbutazone, flunixin meglumine, and ketoprofen in horses. J Am Med Assoc 1993; 202: 71-77.