Test 2: 6 diarrhea Flashcards
small intestine micro anatomy
Slender villi lined by “leaky” epithelial cells
Enterocyte microvilli increase absorptive surface area AND contain digestive enzymes
Crypts = regenerative epithelium
crypts in small intestine contain
regenerative epithelium (also secrete fluid via ANS
stimulation)
— are lymphatic ducts within each villus
lacteals
large intestine micro anatomy
no villi
main job absorb fluid
tight junction
Lymphangiectasia
lacteals which are lymphatic ducts in the villus of the intestine get blocked and become dilated
intestine, what kind of exudate
mucus- catarrhal
caused by endoparasitism &
proliferative enteritis (eg
Lawsonia)
what two viruses will cause hemorrhage in the intestine
(Salmonella, Clostridium
diphtheritic membranes are made of
Fibrin + Hemorrhage Neutrophils + Cell Debris
secondary to virulent pathogens that cause necrosis (salmonella and clostridium)
crypt abscesses in intestine is caused by —
parvovirus
will cause villi blunting, damage and fusion
what causes crypt hyperplasia in intestine
Lawsonia intracellularis
fibrosis in the intestine can lead to
Bowel stenosis→ Altered peristalsis→ abnormal microflora proliferation→ dysmotility!
Lymphangiectasia→ protein exudation/effusion!
Decreased digestion and absorption from loss of enterocytes→ Malabsorp/maldigest!
granulomatous inflammation have what cells
epithelioid macrophages and multi nucleated giant cells
Lymphangiectasia - dilated lymphatic ducts
caused increased hydrostatic pressure and protein losing enteropathy
Lymphangiectasia causes
Increased hydrostatic pressure or decreased lymphatic drainage) → Protein Losing Enteropathy
more fluid in the poop, fluid stays in poop instead of being absorbed and causes diarrhea
intestine
muscular hypertrophy due to
Altered peristalsis: parasites, IBD
Chronic obstruction (FB, intramural mass)
Idiopathic (enteric nervous system?)
muscular hypertrophy of the intestinal wall will predispose — and —
obstruction and rupture
what three things cause muscular hypertrophy of intestinal wall
Altered peristalsis: parasites, IBD
Chronic obstruction (FB, intramural mass)
Idiopathic (enteric nervous system?)
Enteritis
inflammation of small intestine
Ileitis
small intestine (just ileum)
Colitis
colon inflammation
Typhlitis
cecum (typhl- [G] blind)
Enterocolitis
small intestine and colon
Gastroenteritis
stomach and small intestine
Typhlocolitis
cecum and colon
Proctitis
rectum
— is the Secretion of abnormally fluid
feces accompanied by
◼ Increased volume of feces ◼ Increased frequency of
defecation
diarrhea
4 mechanisms of diarrhea
- Hypersecretion
2.Malabsorption/maldigestion
- Exudation/Effusion (passive)
* Damaged or obstructed capillaries, lymphatics, necrosis/erosion/ulcer - Deranged intestinal motility
how does diarrhea from hypersecretion work
bacteria will bind to membrane and secrete enterotoxins activate cAMP and cGMP that cause fluid secretion
will resolve quickly after bacteria is killed
why does fasting have no effect on hypersecretion diarrhea
bacteria linked to cells to cause increased fluid secretion
no function change
what will cause hypersecretion diarrhea
Enterotoxigenic E. coli (ETEC)
hypersecretion diarrhea will cause
dehydration and perineal staining
chyle in lacteals normal but excess watery fluid in GI
what will ETEC do to enterocytes
no damage or ulcers
will just trigger cAMP and cGMP to produce fluid causing hypersecretory diarrhea
4 causes of malabsorption
Microvillus damage/destruction
Absorptive enterocyte necrosis/loss
Crypt cell necrosis/loss
Crypt hyperplasia → Epith. attenuation ( enterocytes will be immature and not absorb as well)
microvillus damage or destruction will cause — grossly
Gross Lesions
– Dehydration
– Watery diarrhea & fecal staining
cells replaced in 3 days
will cause malabsorption diarrhea
microvillus damage or destruction will cause — histo
– Loss of microvillus (brush) border
– Villus enterocyte degeneration/sloughing
will cause malabsorption diarrhea
which Ecoli causes damage to microvilli and causes malabsorption diarrhea
Attaching and Effacing E. Coli (AEEC)
intimin
loss of disaccharidases & absorptive surface area
osmotic diarrhea
AEEC has — that will destroy microvilli
intimin
Attaching and Effacing E. Coli (AEEC)
damage/destroy microvilli → Malabsorption/Maldigestion Diarrhea
what zoonotic pathogen damage/destroy microvilli and causes Malabsorption/Maldigestion Diarrhea
Cryptosporidium (protozoal parasite)
colonizes & destroys microvilli → Enterocyte sloughing & villus blunting → +/- mild inflammation
villus enterocyte necrosis and loss will cause
villus to contract (blunting)
villus fusion
decrease in absorptive SA
immature replacement cells
malabsoption and osmotic diarrhea
enteric — will kill villus enterocytes
coronaviruses/rotaviruses
depending on species will attack more or less of the villi
swine GI normal on bottom
Transmissible Gastroenteritis (TGE) in swine
enteric coronavirus cause severe villus blunting
— are pathogens that kill crypt cells and cause malabsorption diarrhea
“Radiomimetic” viruses
Feline Panleukopenia virus
Canine Parvovirus
Bovine Viral Diarrhea Virus (BVD)
feline panleukopenia virus will kill
bone marrow leukocytes & lymphocytes, crypt cells
cause severe immunosuppression and malabsorption diarrhea
canine parvovirus will kill
lymphocytes and crypt cells
cause immunosuppression and malabsorption diarrhea
pathogenesis of feline panleukopenia
will kill crypt cells
cause villi blunting and fusion
allows for opportunistic infection → Diphtheritic membranes & Septicemia
slow regeneration with immature enterocytes
kills off bone marrow leukocytes & lymphocytes
also has teratogenic effect and causes cerebellar hypoplasia in kittens
clinical signs of K9 and Feline parvovirus
vomiting, malabsorptive
diarrhea, dehydration, sepsis
lesions of K9/FE Parvoviruses
- Necrotizing Enteritis with crypt necrosis
- Peyers Patch Necrosis (punched out)
- Panleukopenia (Cats! All bone marrow lineages affected)
Lymphopenia (cats AND dogs) → GALT depletion, thymic atrophy, lymph node atrophy→ Immunosuppression - **Cerebellar hypoplasia- in utero teratogenic effect- see neuro!
feline small intestin
punched out peyer’s patch
from feline panleukopenia virus (feline parvovirus)→ kills bone marrow leukocytes & lymphocytes and crypt cells
histro of small intestine with feline panleukopenia
kill crypt leads to necrosis and villi blunting and fusion
BVD in the intestine will cause
crypt necrosis
allows for secondary infection to cause Ulcers with diphtheritic membranes
what causes this in pigs and horses
Lawsonia intracellularis
proliferative enteritis -
cause crypt hyperplasia → Malabsorption/Maldigestion Diarrhea
what virulent pathogens will cause exudative/effusive diarrhea through increased capillary or epithelial permeability (damage or obstruction)
Salmonella (ZOONOTIC)
Clostridium perfringens
clinical signs of K9 and Feline parvovirus
vomiting, malabsorptive
diarrhea,dehydration, sepsis
what virulent pathogens will cause exudative/effusive diarrhea through Lymphatic obstruction → protein losing
enteropathy (PLE)
Granulomatous inflammation (Johne’s disease)
Neoplastic infiltrates (diffuse lymphoma = LSA)
two ways to cause exudative/effusive diarrhea
Increased capillary or epithelial permeability
(damage or obstruction)
Lymphatic obstruction → protein losing enteropathy (PLE)
exudative diarrhea leads to — membranes
diphtheritic- Fibrin, Hemorrhage, Neutrophils, Cell Debris
Pathogen #1 that kill villus enterocytes AND damage the lamina propria
Salmonella spp.
cause malabsorption and exudative diarrhea
LPS/endotoxin- cause necrosis and hemorrhage of lamina propria and enterocytes
Pathogen #2 that kill villus enterocytes AND damage the lamina propria
Clostridium perfringens & C. difficile (HORSES!)
Necrotizing to necro-hemorrhagic enterocolitis
exotoxins burn tissues and damage blood vessels
Mucosal necrosis with diphtheritic membranes
(can look similar to Salmonella)
Pathogens/processes that cause Infiltrative disease→effusion/exudation
Lamina propria infiltration → increased hydrostatic pressure → prevents absorption (fluid, nutrients, lymph) → Lacteal dilation (lymphangiectasia)→ effusion
Granulomatous enterocolitis- Johne’s dz & Diffuse alimentary lymphoma (“LSA”)
johne’s disease is caused by
Mycobacterium avium subsp. paratuberculosis
Acid-fast, facultative intracellular bacillus
- Endemic in cattle herds (dairy>beef) →chronic diarrhea & emaciation
via Protein-Losing Enteropathy (PLE)
Johne’s disease is infiltrative and causes — kind of diarrhea
effusion/exudation
(Mycobacterium paratuberculosis)
Protein-Losing Enteropathy (PLE)
Johne’s disease is infiltrative and causes — kind of diarrhea
effusion/exudation
(Mycobacterium paratuberculosis)
Protein-Losing Enteropathy (PLE)
what does Johne’s disease lesions look like
Thickened “corrugated” mucosa
– Multifocal mucosal erosions
– Enlarged mesenteric lymph nodes
Johne’s disease
causes
Diffuse —-Enterocolitis
(ileitis/typhlitis/colitis) → inflammation extends
Mesenteric —
→Villus blunting & fusion, lymphangiectasia
—- (PLE)
→ hypoproteinemia → emaciation
Granulomatous
lymphadenitis
Protein-Losing Enteropathy
—- →decreased contact time with mucosa→ maldigestion/malabsorption →2°secretory or osmotic diarrhea
hypermotility
—→ bacterial overgrowth→ toxic substance production or reduced fermentation →2°secretory or osmotic diarrhea
hypomotility
causes of abnormal motility
Physical stimulus or obstruction: parasites
Muscular hypertrophy (IBD, Idiopathic)
Peritonitis
what are some Physical stimulus or obstruction that lead to abnormal GI motility
Parasites, foreign bodies, strictures intraluminal or mural mass
- eg lymphoma, adenocarcinoma, leio
what causes GI muscular hypertrophy
IBD
idiopathic
intestinal response to injury
—- : Catarrhal, hemorrhagic, diphtheritic membranes, blunting
acute
intestinal response to injury
—- : fusion, crypt abscesses, crypt hyperplasia, epithelial attenuation
subacute
intestinal response to injury
—- : fibrosis, granulomatous inflammation (nodular or diffuse), lymphangiectasia, muscular hypertrophy
chronic
4 Basic Mechanisms of Diarrhea
- Hypersecretion: ETEC
- Malabsorption maldigestion
- Effusion/exudation
- Dysmotility
what causes hypersecretion diarrhea
ETEC
Malabsorption maldigestion by Microvillus damage is by
AEEC, Cryptosporidia
Malabsorption maldigestion by Villus Enterocyte Necrosis is by
Enteric Coronaviruses
Malabsorption maldigestion by Crypt Cell Necrosis
FE Panleukopenia (feline parvo),
BVD
Malabsorption maldigestion by Crypt Hyperplasia
Lawsonia intracellularis
Effusion/exudation diarrhea by Lam. propria necrosis→hemorrhage is by
Salmonella
Clostridium
Effusion/exudation diarrhea by Lam propria infiltration→lymphangiectasia:
Johne’s dz (Mycobacterium avium paratuberculosis)
LSA
Dysmotility diarrhea by Physical obstruction from parasites such as
ascarids
Dysmotility from Muscular hypertrophy is by
IBD
idiopathic
