8.3 Pathology of Stomach and Abomasum

What is gastric dilation, displacement and volvulus (GDV)?

In large, deep-chested dog breeds

Gas, fluid or feed block the cardia, which prevents eructation and emesis

Gastric rotation - pylorus obstructed. prevents passage of contents into small intestine

Gas result of aerophagia or may come from carbon dioxide produced by physiologic processes

What are reasons for GDV?

Gastric rotation occurs due to recurrent dilation, overfeeding or postprandial exercise

Repeated episodes - result in stretching and relaxation of gastrohepatic ligament

What is the rotation and infarction of GDV?

Clockwise rotation on a ventrodorsal axis - 180 or 360°

V-shaped bending or enlarged spleen

Venous infarction

Compression of diaphragm, vena cava and portal vein → decrease of venous return → decreased cardiac output and perfusion of abdominal viscera → shock → death

Rupture of the stomach

What are signs of inflammation in gastritis?

Acute/chronic

Catarrhal

Haemorrhage - clostridia, uraemia, fungal

Ulcerative/necrotising - NSAIDs. uraemia

Proliferative/hyperplastic

What are causes of of gastritis?

Dogs and cats - uraemia. parasites. allergic/immune-mediated

Pigs - infectious. colibacillosis. salmonellosis

Ruminants - clostridia. fungi. parasites

Horses - parasites

What is traumatic gastritis?

Ingestion of foreign bodies (dogs and cats)

e.g:

Corn cobs. Sticks. Stones. Bones. Toys etc

What types of gastritis are there?

Helicobacter spp. - stomach of dogs and cats

Mycotic gastritis - granulomatous inflammation by Histopplasma capsulate

Parasitic gastritis

What is Braxy?

Type of gastritis

Caused by Clostridium septicum

Haemorrhagic and necrotising abomasitis

Lambs more affected than calves

Usually associated with cold weather

What is mycotic abomasitis?

Angioinvasive fungi such as Aspergillus, Mucor, Absidia

Results in vasculitis and thrombosis → haemorrhage infarction in the mucosa

Round, target-like lesions are typical of fungal infections

How does gastric ulceration happen?

Gastric or abomasa ulcers can be seen incidentally in any species

Stress and mucosal hyper perfusion - imbalance between necrotising effects of gastric acid/pepsin secretion and mucosal protective mechanisms

Non-steroidal anti-inflammatory drugs (NSAIDs) in high doses - depresses prostaglandin formation. leads to decreased secretion of protective bicarbonate

What causes gastric ulceration?

Local mucosal physical injury

Local hypoperfusion and ischemia

High gastric acidity - mast cell tumours release histamines. leads to acid hyperexcretion. Zoellinger-Ellison syndrome is a tumour-associated cause is gastrin-secreting pancreatic islet cell tumours or gastrinomas

NSAIDs - decreased PG → vasoconstriction → decreased mucus production → necrosis

Uraemia - damage to endothelial cells → vascular compromised increases ammonia secretion → caustic injury → necrosis

Multfactorail in pigs

Infection and inflammation - angioinvasive fungi in cattle. Helicobacter

What is gastric ulceration in pigs and horses?

Pigs - at the pars oesophageal, frequency bleed and can cause exsanguination

Horses - in foals (idiopathic). adults (NSAIDs)

What is uremic gastropathy?

Dogs and cats - due to chronic renal disease

Gross findings - oedema, haemorrhage, ulceration

Pathogenesis - vascular damage from uremic toxins → ulceration, necrosis

Mineralisation

What are the 2 types of toxic gastropathies?

Blister beetle toxicosis

Heavy metal toxicosis

What is blister beetle toxicosis?

Horses eating alfalfa hay infested with blister beetles

Necrohaemorrhagic gastroenteritis, haemorrhage ulcers in the bladder and myocardial necrosis

Causative toxin - cantharidin

What is heavy metal toxicosis?

Arsenic, zinc

Haemorrhage, necrosis and ulceration in stomach or abomasum

How can we classify gastric neoplasia?

Epithelial - Polyp/adenoma (mucosal lining and glands). Adenocarcinoma (mucosal lining and glands). Squamous cell carcinoma (linked to equine papillomavirus-2 infection)

Mesenchymal - Leimyoma/leimyosarcoma (from muscle layer/tunica muscularis)

Round cell - lymphoma (from mucosa-associated lymphoid tissue)

What are neoplasias in the abomasum?

Lymphoma is most common

Usually associated with bovine leukosis virus