Diseases of simple stomach

Question 1

What are five defenses of the gastric mucosa to injury?

Answer 1

Tight junctions between epithelial cells
HCO3- secretion
PGE2 action
Mitotic ability of ithmus cells & constant epithelial turnover
Mucoid glycocalyx layer

Question 2

What are the three major responses of the gastric mucosa to injury?

Answer 2

1. Restitution (repair; begins within minutes)
2. Atrophy - usually of specialist cell types
3. Mucous metaplasia and hyperplasia - proliferation of mucous neck cells, thickened nodular mucosa with less specialist function

Question 3

What are two consequences of glandular metaplasia of the gastric epithelium?

Answer 3

Diarrhoea

Malnutrition

Question 4

Give four potential causes for gastric/abomasal impaction.

Answer 4

Poor mastication of food due to dental disease
Vagal nerve damage causing functional stasis
Feeding low quality roughage to dehydrated stock
Blockage of the pylorus (neoplasm, FB)

Question 5

Briefly describe the process of gastric dilation. Which species are most prone ?

Answer 5

Pigs and horses - due to grain/concentrate overload
Get swelling of ingesta with saliva and gastric secretions, gas and lactic acid production by bacteria of saccus caecus, osmotic movement of water into stomach, dehydration, hypovolemic shock, respiratory distress, possible gastric rupture, death

Dogs due to aerophagia/gastric volvulus

Question 6

What three features can help you distinguish if gastric rupture was post-or antemortem?

Answer 6

A true antemortem rupture should have:

• haemorrhage along tear line
• local inflammation e.g fibrin, redness
• wide spread of gastric contents throughout abdominal cavity

Question 7

What clinical sign might be seen in a dog with pyloric stenosis?

Answer 7

Forceful vomiting shortly after eating

Question 8

What are the two primary mechanisms for pyloric stenosis?

Answer 8

Idiopathic hyperplasia and hypertrophy of the smooth muscle of the pyloric sphincter

Obstruction of pylorus by foreign body, neoplasm etc

Question 9

Which direction does the stomach rotate in GDV?

Answer 9

Clockwise about the cardia

Question 10

What position does the spleen usually assume in GDV?

Answer 10

Right ventral

Question 11

What factor predisposes dairy cows to abomasal displacement? When are they at greatest risk?

Answer 11

Genetically predisposed to shuttle abnormal amount of bodily Ca2+ into milk production, producing a hypocalcemia. This affects smooth muscle contraction and can predispose to abomasal displacement. Most likely to occur just before parturition and for the 6 weeks afterward, when milk production is highest; also ration is typically grain-heavy.

Question 12

Which (L or R) abomasal displacement is less serious? Why?

Answer 12

Left is less serious

Right usually involves volvulus of abomasum and venous compromise of abomasum, omasum. Risk of major damage to vagal nerves

Question 13

Where does the abomasum go in L sided displacement? How to correct?

Answer 13

Sits up against left flank between rumen and body wall.

Can correct by rolling cow

Question 14

What are the clinical signs of a dog with gastric ulcers?

Answer 14

Variable appetite
Abdominal pain
Vomiting +/- blood
Melena
Anemia

Question 15

What are three potential causes of gastric ulcers in dogs?

Answer 15

1. Mast cell tumours
2. Gastrinomas > secrete gastrin
3. Uraemia

Question 16

How does stress play a role in gastric ulcer pathogenesis?

Answer 16

1. SNS tone inhibits GIT motility - acidic contents sit in lumen for longer
2. SNS tone reduced blood flow to gastric mucosa
3. SNS causes cortisol release which reduces bloodflow to gastric mucosa

Question 17

What might be two signs of abomasal ulcers in cattle?

Answer 17

Anemia

Melena

Question 18

Which region of the pig stomach is most prone to ulceration? What process typically precedes ulceration?

Answer 18

The pars oeseophagea

Hyperkeratosis - may be yellowed by bile reflux

Question 19

What is one potential consequence of pars oesophagea ulceration for production pigs?

Answer 19

Scarring and contraction of this area can reduce the size of the cardiac sphincter, preventing animals from gaining as much weight

Question 20

What 4 factors might contribute to squamous gastric ulcers in horses?

Answer 20

1. Infrequent feeding (acid splash up to saccus caecus)
2. Intense exercise (big increases in abdominal pressure + inhibitory effect of exercise on gastric emptying and blood supply)
3. Stress
4. Concentrate-high diets increasing acidity of contents

Question 21

What factors might contribute to glandular gastric ulcers in horses?

Answer 21

NSAIDs
Stress
+/- helicobacter?

Question 22

What are three potential causes of chronic gastritis? What is an important consequence?

Answer 22

Gastric parasitism
Lymphocytic-plasmocytic gastritis
Food allergy

Achlorhydria - absence of HCl in gastric secretion

Question 23

What is Gasterophilus spp.? Which species does it affect, and what are the consequences?

Answer 23

Bot fly larvae - small erosions and ulcers in HORSE stomach mucosa, generally inconsequential

Question 24

What is Braxy? What causes death and what lesions may be seen?

Answer 24

Eating frozen pasture contaminated with Clostridium septicum leading to death by exotoxaemia. Get oedematous submucosa of stomach due to increased permeability and submucosal emphysema

Question 25

What is the normal pH for monogastric stomach fluid?

Answer 25

Less than 3.0

Question 26

What is the normal pH for abomasal fluid?

Answer 26

3.5 - 4.0