Gastrointestinal Pathologies

Study Notes

Expanding stomach can compress thoracic cavity, leading to respiratory distress
Gastric mucosal barrier protects normal mucosa from harsh chemical environment of gastric luminal contents
pH of gastric luminal contents is 2, while mucous layer maintains a pH of 4-6
GI barrier is maintained by protective layer including mucosal cells, tight junctions, prostaglandins, and mucus
Prostaglandins help maintain GI mucosal blood flow and integrity, increase mucus and bicarbonate secretion, and decrease acid secretion
Defect in GI mucosal barrier leads to self-perpetuating cycle of mucosal damage, injury, and inflammation

Inflammatory Bowel Disease (IBD) is a group of GI diseases characterized by persistent clinical signs and histologic evidence of inflammatory cell infiltrate of unknown etiology
IBD includes granulomatous enteritis (GE), lymphocytic-plasmacytic enterocolitis (LPE), multisystemic eosinophilic epitheliotropic disease (MEED), and idiopathic focal eosinophilic enterocolitis (IFEE)
Disease is characterized by infiltration of small and large intestine with inflammatory cells, including lymphocytes, plasma cells, macrophages, and eosinophils
Several factors may be involved, including GI lymphoid tissue, permeability defects, genetic, ischemic, biochemical disorders, infectious and parasitic agents, dietary allergens, and drug reactions

Mast cell degranulation occurs, causing histamine release that perpetuates further gastric acid secretion
NSAID administration, neoplasia, and hepatic disease are the most common causes of GI ulcers in dogs
NSAIDs can cause direct topical damage to GI mucosa and inhibition of COX-1, leading to decreased production of protective prostaglandins
Corticosteroids potentiate the effects of mucosal damage by decreasing cell mucus production and stimulating acid production

Grain overload is an acute disease of ruminants characterized by rumen hypomotility to atony, dehydration, acidemia, diarrhea, and in severe cases, death
The disease is most common in cattle that accidentally gain access to large quantities of readily digestible carbohydrates, particularly grain