Clinical Conditions

4.3.1 Horse

Gastric ulceration: Erosion and even perforation of the gastric mucosa is of high inci­dence. The factors involved are multifactorial with stress, exercise and diet all of proven involvement.

Gastric impaction: This is not a common condition and tends to occur alongside a recurrence of colic (see Section 6.3). The retention of gastric contents occurs when the feed swells or when there are dental problems affecting the ability to chew the food adequately.

Gastric dilatation and rupture can be a sequel to impaction or to small or large intes­tinal obstruction. Rupture usually occurs along the greater curvature of the stomach.

4.3.2 Ox

Vagus indigestion (see Section 11.5): This is a chronic syndrome of indigestion in ruminants but mainly cattle. Various causes have been suggested, but the condition seems most likely to be due to damage to branches of the vagus nerves as a consequence of traumatic reticuloperitonitis. Loss of appetite, reduced milk yield, weight and condi­tion loss and abdominal distention are clinical signs. The prognosis is poor.

Displaced abomasum: The abomasum is fairly mobile, being only loosely anchored by the greater omentum (see Section 3.2 and 3.3). During pregnancy the position of the abomasum becomes altered by the presence of the pregnant uterus. Displacement can be either to the left or right although more commonly to the left, where it becomes trapped ventral to the rumen. Accumulation of gas and obstruction to movement of ingesta occur with a left displacement. The situation is more serious with a right dis­placement since haemostasis and damage to the vagal nerves are likely to result from torsion of the abomasum. Loss of appetite and condition in a recently calved cow are usual indicators of displaced abomasum, and diagnosis is confirmed by auscultation with a stethoscope when a characteristic sound is heard.

Bloat: This condition can occur as a result of engorgement of lush pasture. Accumulation of fermentation gas leads to distention of the rumen with resulting pres­sure on the heart and lungs. Death can result without emergency attention usually involving the insertion of a trocar and cannula into the rumen in the left dorsal flank.

4.3.3 Sheep

Bloat: Although not as common as in cattle, the sheep's stomach is susceptible to bloat. Internal parasites in the gastrointestinal tract can be responsible for loss of condition.

4.3.4 Pig

Gastric ulceration: Growing pigs are the most susceptible to ulceration of the stomach. Erosion and ulceration of the mucosa in the oesophageal of the stomach can occur for a variety of reasons, e.g. too small particle size of the diet.

Gastric torsion: Overfeeding and large amounts of wet feed can be causative factors of gastric torsion. Swollen abdomen and sudden death (2-3 hours) are presenting signs. The torsion is often not restricted to the stomach but can involve the intestines as well. Dilatation of the stomach and congestion of blood vessels are usual findings at post-mortem.

4.3.5 Dog

Gastritis: Inflammatory conditions of the stomach are common in the dog. The causes are many including contaminated food, ingested irritants and toxic plants. The patho­genesis involves damage to the mucosa and an inflammatory response. The clinical signs are vomiting, anorexia and depression.

Gastric dilatation and volvulus (GDV): This condition is of frequent occurrence in large breed dogs, e.g. Great Dane, Irish Setter, Gordon Setter, Weimaraner and St. Bernard. The mortality rate is high (33.3% in one study). The cause is not clear but there does seem to be a predilection in barrel-chested individuals of the breeds above and other large breeds. Stress and overeating have been identified as possible causes but not proven. The pathogenesis of GDV involves gastric dilatation followed by gastric rota­tion leading to ischaemia and necrosis of the mucosal and smooth muscle layers of the stomach wall. Prompt shock therapy and surgical correction of the rotation are the nec­essary procedures.

Foreign bodies: The ingestion of foreign bodies is frequent in dogs and involves a variety of objects. The author once removed nine golf balls from the stomach of a German Shepherd! Vomiting is the most likely clinical sign of a gastric foreign body. Palpation rarely detects an object in the stomach, and radiography depends on the nature of the foreign body. Longhaired cats often ingest hair that may accumulate as a hairball in the stomach. Surgical removal of the foreign body is usually indicated.