C15 Gastrointestinal Pathology II Flashcards
Stomach/abomasum
If empty, normal pH:
- carnivores
- herbivores
- Carnivores <3
- Herbivore <3.5-4.0
what type of epithelium is prone to acid damage?
Stratified squamous epithelium
Stomach: Response to injury
- superficial damage repair?
- how?
- Superficial damage is rapidly repaired by epithelial migration
<><><><> - Fibrin, sloughed cells, mucus Cover defects and protect from acid, allow healing
- Flattened epithelium = ‘stretched’ to cover defects
- Progenitor cells in isthmus proliferate later
- Increased blood flow
> Dilutes and removes excess acid absorbed by damaged areas
Stomach: Response to injury
> Mucous metaplasia/hyperplasia
- associated with?
- how can achlorhydria arise?
- common causes
- seen near what?
Mucous metaplasia/hyperplasia: associated with chronic inflammation
o Parietal cells are replaced with goblet cells, can lead to achlorhydria
o Many possible causes, but nematodes (Ostertagia spp.) most common
o Also seen near healing ulcers
Stomach: Response to injury
> Achlorhydria
- what is it
- how bad can it get and why thats a problem
- main issue?
- additional issues? signs?
Achlorhydria: insufficient acid production
o If severe, gastric pH can approach neutral (allows microbial growth)
o Main problem is inappetence, NOT impaired digestion
o Protein lost through mucosa -> loss of efficiency +/- weight loss
o Can also predispose to invasion of pathogens (bacteria, fungi)
Stomach: Dilation and displacement in the horse
- causes
- types
- survivors may get what?
- sequelae?
- Usually due to ileus or grass sickness (secondary dilation)
- Primary dilation due to excess carbohydrates, water, or lush pasture forage
o Survivors may develop laminitis - Either may lead to rupture (idiopathic rupture also possible)
o Fairly common cause of colic
stomach rupture in horse
- where? how can we tell vs perforation?
- how can we tell not post mortem lesion
- bloat line?
- cause of death?
<><><><>
- causes of perforations? occurence?
- Usually greater curvature
- Tear longer on serosa than mucosa
- Surrounding hemorrhage = not postmortem
- May have a bloat line
- Cause of death?
o Shock
o Peritonitis
<><><><>
Perforations less common
o Ulcers
o Parasites
o Neoplasia
Gastric dilation and volvulus in dogs
- signalment
- associated with?
- rotates how?
- Gastric dilation and volvulus: common in deep chested breeds, rare in cats o Usually associated with eating +/- aerophagia
o Predisposing factors poorly understood
<><><>
Gradual dilation, if unresolved….
…rotates clockwise from transverse to longitudinal orientation
Gastric dilation and volvulus
- simple dilation vs volvulus > where are esophagus and spleen?
- splenic infarct risk?
o In simple dilation, esophagus is patent and spleen stays on the left
o Recurrent dilation predisposes to splenic infarcts
o In volvulus, the spleen ends up on the right with venous infarction +/- rupture
Complete occlusion of esophagus
- causes what effect on stomach?
- how do we get to hemoabdomen, and death?
- what animals?
Complete occlusion of esophagus -> venous infarction of stomach due to obstruction
> Stomach becomes red-black, bloody contents, can rupture
> Can cause blood vessel avulsion and hemoabdomen
> Venous obstruction and pressure from distended stomach decrease venous return
> Circulatory shock, respiratory distress from pressure on diaphragm
> Death if not treated quickly!
<><><><>
dogs?
Adult sows fed infrequently
Abomasal displacement and volvulus
- signalment
- timing?
concurrent conditions
Abomasal displacement and volvulus: common in intensively managed dairy cows
o Most common around parturition, atony likely involved
o Often concurrent metritis, ketosis, hypocalcemia +/- retained placenta
LDA
- common? hard to treat?
- possible complications of surgery?
- PM > watch out for what?
- Left displacement: most common, easily treated
o Can lead to fistulas if sutures penetrate the mucosa - Like all displacements, can reduce during PM positioning!
RDA
- common?
- proportion combined with volvulus?
- metabolic consequence?
- other consequences? sequelae?
- twist orientation?
Right displacement (15% of cases):
o Simple right displacement can be complicated by volvulus (20% of cases)
o Duodenal outflow obstructed -> chloride sequestration -> alkalosis
o Can also obstruct blood vessels and damage nerves
<><><><>
- Blood-tinged fluid and gas
- Venous infarction can lead to rupture and peritonitis
- If there is nerve damage, motility cannot be restored: vagal indigestion
<><><><>
Counterclockwise when viewed from right side
Pyloric stenosis
- species?
- congenital vs acquired causes
<><><><>
- what is Chronic hypertrophic pyloric gastropathy
> signalment?
> signs?
- appearance
- Common in dogs, rare in cats and horses
<><><><> - Congenital: poor growth, recurrent vomiting post-weaning
o May have smooth muscle hypertrophy
<><><><> - Acquired: stricture, foreign bodies, polyps, neoplasia
o Chronic hypertrophic pyloric gastropathy in dogs
<><><><>
Chronic hypertrophic pyloric gastropathy
o Mucosal and/or muscular hypertrophy
o Middle aged, small breed dogs, males > females
o Chronic, intermittent vomiting, weight loss, +/- gastric distention - Enlarged mucosal folds obstruct the pylorus
Stomach: Foreign bodies
- can cause
*Often incidental and can be virtually anything
* Low roughage Rumen more common
*Can cause vomiting, gastritis, ulcers
* Rare causes of pyloric obstruction and death
Stomach: Impaction - horse, cow, sheep
- cause?
- may cause what? R/O?
- Fibrous feed, poor chewing, low water intake
- May cause colic, loss of condition, anorexia; rule out dilation
Stomach: Impaction - horse, cow, sheep
- primary vs secondary
- sequelae?
- possible breed assoc?
- Primary: low water intake or fibrous feed
- Secondary: stenosis, vagus indigestion
<><> - Can rupture (especially primary), causing peritonitis
- Often severe metabolic alkalosis and reduced K+ from inanition
<><><><> - Abomasal dilation and emptying defect in Suffolk and Hampshire breeds
- Massive abomasal distention, contents are similar to normal rumen content
- Cause unknown – genetic predisposition to dysautonomia?
Gastritis
- Presumptive diagnosis for:
- Presumptive diagnosis for vomiting believed due to gastric irritation
Uremic gastritis
- species
- can cause what
- lesions?
Uremic gastritis: some dogs, cats, horses with uremia
o Severe congestion and hemorrhage, often causes hematemesis, melena
o Variable lesions, from minimal to gritty, red-black necrosis
Mechanical gastritis
- what animals?
o Most common in dogs with foreign bodies, cats with hairballs
chemical gastritis
- cause in horses?
- cause generally?
o Cantharidin toxicity from blister beetles in horses
o Zinc toxicity (causes gastric necrosis)
True inflammatory gastritis
- species?
- associated with?
o Mostly carnivores, not usually infectious
o Usually associated with systemic inflammation (ex. food allergy)
helicobacter as a cause of gastritis in animals
- is it?
o Implicated in human gastritis but more tenuous link in other species
o Most mammals have their own Helicobacter species but most are nonpathogenic
o Exceptions: ferrets and cheetahs
o No evidence these predispose to neoplasia
Gastroduodenal ulceration
- pathogenesis (peptic ulcer)
- Peptic ulcer: imbalance between mucosal integrity and effects of gastric acid
o Usually problems with repair rather than acid secretion
o Acid hypersecretion: gastrinoma, histamine release from mast cell tumours
o Impaired protection: NSAIDs (inhibit bicarbonate, alter blood flow)
o Duodenal reflux: bile salts damage cells
o Regardless of cause, breach of mucosa can lead to ulceration
<><>
Ulceration progresses via coagulative necrosis (recall it is acid damage)
Duodenal ulcers for where?
- pathogenesis?
- Duodenal ulcers usually form between the pylorus and bile/pancreatic duct
o Pathogenesis similar to gastric ulcers
signs of repairing gastroduodenal ulcer
- Raised edges
- Granulation tissue bed
possible sequelae of gastroduodenal ulcers
- Ulcers that reach the submucosa are at increased risk of hemorrhage
- ulcers at proximal duodenum / pyloris can lead to stricture
- If they erode all the way through = perforation
- In the pylorus or duodenum can cause thrombosis
Gastroduodenal ulceration
- Glucocorticoids released during stress can have what impact?
- how does blood from a gastric ulcer look on its way out?
- Glucocorticoids released during stress can cause gastric hemorrhage
o Ex. surgery, trauma; related to effects of reduced perfusion? - Blood from damaged mucosa turns brown-black when exposed to acid
- If enough digested blood reaches the intestines = melena
Gastroduodenal ulceration in dogs
- how common? what location?
- can cause what blood vessel related issue?
- what happens if perforation?
- Uncommon, usually in the pylorus or duodenum and cause thrombosis
- Perforation releases feed into abdomen, chronic inflammation if blocked by omentum
mast cell tumours contribution to peptic ulceration in dogs
- Mast cell tumours can cause peptic ulcers, even if not directly involving stomach!
o Usually clinically silent
Zollinger-Ellison syndrome in dogs
- what is this?
- consequences?
Zollinger-Ellison syndrome: ulcers due to gastrin-secreting neoplasm
o Pancreatic neoplasia or gastrinoma
o Metastasis common, often also have reflux esophagitis
Gastroduodenal ulceration in cows
- how common? locations
- signalment?
- contributing factors?
- relatively common outcome?
- Common in abomasum, rare in duodenum
o Veal calves > > > other calves, dairy cows, feedlot cattle - Often stress-related and subclinical, tend to present with melena
- Perforation is a relatively common cause of death in calves
o Lethal hemorrhage +/- peritonitis
Gastroduodenal ulceration in pigs
- location?
- how common?
- clinical signs?
- age?
<><><><>
- pathogenesis for pigs, esp.
- outcome? signs?
- Limited to pars esophagea (squamous), very common and usually subclinical
o Weaned growers and feeders - Sometimes cause runting, anorexia, anemia, and sudden death
<><><><> - Finely ground feed
> Watery contents that equalize pH instead of partitioning
> Parakeratosis, fissures, erosion (yellow, thick, irregular, peels easily)
> Ulceration (deeper bleeding, may stricture if heal via scarring)
> Fatal hemorrhage (relatively common, look for clots, melena, pallor)
Gastroduodenal ulceration in horses
- cause?
- what can it cause?
- most common in what signalment?
- anatomical location
- pathogenesis?
- possible outcomes
- Often incidental but can cause colic in adults and foals
- Very common in <4 month old foals, performance horses (stress-related?)
- Often form in squamous epithelium near margo plicatus
- Similar pathogenesis and progression to pigs
- Sometimes can perforate or form strictures
