Page 748 - The Veterinary Care of the Horse

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Figures 17.3a and b (Courtesy of Dr M. J. Murray): a) normal gastric squamous mucosa adjacent to margo plicatus; several
Gasterophilus spp. larvae are attached; b) mild multifocal erosions in the gastric squamous mucosa adjacent to the margo
plicatus

The squamous part of the stomach is very sensitive to acid and is a common site for
gastric ulceration (Figure 17.3b). The glandular region has a bicarbonate-rich mucous lining

which helps protect it from the harmful effects of acid.

The incidence of gastric ulcers

Gastric ulceration is very common in performance horses and is the most common disorder

of the equine stomach. As many as 90% of Thoroughbreds in training have gastric ulcers,
together with up to 60% of horses competing and working in other disciplines. It can also be

a significant problem in foals. The incidence is low in horses that are turned away at grass.

EGUS is now considered to be two separate syndromes. Ulcers commonly occur close to
the margo plicatus, in the squamous part of the stomach. This is referred to as equine
squamous gastric disease (ESGD). They also occur in the glandular portion, particularly near

the pylorus where the stomach opens into the duodenum; this is known as equine glandular
gastric disease (EGGD). In both syndromes there is a wide spectrum of severity ranging from

mild inflammatory changes to deep, bleeding erosions of the stomach lining. In severe cases,
the ulceration extends to the oesophagus and duodenum. Fatal perforation occasionally
occurs.

Causes and predisposing factors

DIET

Horses continually produce acid in their stomachs. In the wild, when a horse is grazing for up