Intestinal Pathology Flashcards
What is the difference between malabsorption and maldigestion?
Malabsorption = Damage to epithelial layer –> contraction (shorter, stunted, blunted) –> less surface area, less function, ↓absorption/↑leakage of bacteria/toxins, etc
Maldigestion = Lack of enzymes and bile results in little to no breakdown of large molecules Water drawn in due to ↑osmotic pressure in intestinal lumen (diarrhea)
What are the clinical signs of intestinal dysfunction? How do these signs typically present?
Abdominal Pain (Colic in large animals)
Vomiting
Diarrhea - Acute or Chronic +/- weight loss/ascites
Constipation
May be present together or as part of systemic condition
What is the difference between volvulus and torsion?
Volvulus is twisting across the short axis (mesenteric axis)
Torsion is twisting along the long axis
How does venous congestion occur?
Thin walled veins get compressed = venous congestion
What is the highest risk associated with ischemic infarction?
Necrosis
Volvulus
Congestion
Describe presentation of upper intestinal tract obstruction
Presentation usually acute and severe
Fluid/gas above obstruction
Vomiting
Metabolic alkalosis (loss of acid in vomitus)
Dehydration
Reduced renal flow and resultant uremia
Describe presentation of lower intestinal tract obstruction - Is it more or less acute than upper intestinal tract obstruction?
Less acute than upper intestinal tract
Still allows function of intestinal tract above obstruction
Increase in fluid resorption proximal to obstruction - Decreased vomiting
Eventual metabolic acidosis due to dehydration and catabolism of fat/muscle (producing keto acids)
Animal no longer receiving nutrients from digestion, breaking down muscle/fat instead (ketoacidosis)
Intussusception
External obstruction - pedunculated lipoma
Explain how neoplasia can create an external obstruction in the intestines
Portion of mesentery grows benign fat-filled tumor (pedunculated lipoma) and is slightly mobile within abdominal cavity
Wraps around gut, causes strangulation effect
What are the clinical signs associated with strangulating lipoma?
Leads to colic signs
Can lead to necrosis/rupture
What role does fibrin have? What does it cause in the abdominal cavity?
Part of clotting/inflammatory cascade
Coats abdominal cavity and organs and leads to fibrinous peritonitis
Noted on PME
Fibrin
What are the 4 basic mechanisms of the pathogenesis of diarrhea?
Do these mechanisms occur in SI, LI or both?
- Malabsorption
- Altered structure/permeability - Secretory Diarrhea
- Altered epithelial cell transport - Maldigestion
- Osmotic effects - Altered Motility
Work in both SI and LI
Give viral causes of diarrhea
Rotavirus
Coronavirus
Parvovirus
Give bacterial causes of diarrhea
Campylobacter
Salmonella
Clostridium (perfringens type A, difficile)
Give parasitic causes of diarrhea
Endoparasites
Cyathostomins
Toxacara
Give protozoal causes of diarrhea
Cryptosporidium
Coccidiosis
What are the 2 main systemic consequences of diarrhea?
Loss of water
- Dehydration, Hemoconcentration, Hypovolemic shock
Loss of ions
- Na, K (hypokalemia), Bicarbonate (metabolic acidosis)
Label the targeted injury sites of virus on the intestinal villus
What kind of infection is this?
What kind of infection is this?
How does parvovirus replicate?
What kind of cells does it target?
What is a classic pathological sign of degeneration by parvo?
Can only replicate with DNA polymerase
Targets rapidly dividing cells (intestinal crypts, cells in gut replicate quickly)
Classic sign of degeneration = peyer’s patches (punched out holes)
How does salmonellosis cause damage to the gut? Where in the gut does it usually target? Where do you normally see lesions in the intestine and what structures in the gut do the lesions typically overly?
Salmonella produces endotoxin/exotoxin in the gut
Affects ileum, cecum and colon
Causes severe multifocal mucosal damage
Often overlying submucosal lymphoid tissue
What is another name for clostridial colitis in the horse?
Colitis X
How does clostridial colitis cause damage to intestinal mucosa? How is the distribution different than other infections? Why?
Colonize mucosa extensively and release soluble toxins (exotoxins) –> necrosis/hemorrhage
Distribution is slightly different - tissue is diffusely dark red, entire tissue uniformly affected because exotoxins affect ENTIRE surface
What are exotoxins vs endotoxins?
Exotoxins - soluble toxins
Endotoxins - Lipid A part of lipopolysaccharide (LPS) portion of gm- bacterial wall
What is this? What are all the tiny dots
Cyathostominosis - all the tiny dots are strongyles on mucosa
Describe the pathogenesis of cyathostominosis?
Tiny nematodes inside the mucosa which cause huge damage to the intestines –> diarrhea/water loss
If an animal has chronic diarrhea +/- weight loss, what are the top differentials?
chronic enterocolitis
lymphangiectasia
endoparasitism
neoplasia
grass sickness
What is another name for chronic enterocolitis? What are the 3 types? Which cells dominate each of these 3 types?
Inflammatory Bowel Disease
Lymphoplasmacytic - inflammatory cells
Eosinophilic - eosinophils
Granulomatous - macrophages/giant cells
What is lymphangiectasia?
Lymphangiectasia is an intestinal disease whereby the lymphatic fluid of the body is leaked into the gastrointestinal tract.
The condition results in a loss of protein from the body and can lead to your dog becoming seriously ill.
What is grass sickness?
Grass Sickness is a disease of horses, ponies and donkeys in which there is damage to parts of the nervous system which control involuntary functions, producing the main symptom of gut paralysis. The cause is unknown but the nature of the damage to the nervous system suggests that a type of toxin is involved. The disease occurs almost exclusively in horses with access to grass.
What is inflammatory bowel disease?
Syndrome associated with persistent gut inflammation (idiopathic inflammation of the gut)
What is protein losing enteropathy? What is it a consequence of and how does loss of protein occur? What is the main protein lost? What does this lead to?
Consequence of excessive inflammation in the gut
Inflammatory cells travel into the intestines and release inflammatory mediators (cytokines, prostaglandins, etc.) which make epithelium/blood vessels more leaky
This causes increased permeability to plasma proteins (albumin)
Hypoalbuminemia → ↓plasma osmotic pressure → edema and ascites +/- wasting and/or emaciation
What is this?
Villous atrophy
Blunting/Stunting and Fusion of villous ends
What is this?
What is this (Hint: Cat)? What does it lead to?
What type of endoparasite causes issues with malabsorption? Where does it get its name from and how does this malabsorption occur?
Cyathostominosis causes malabsorption
L1/L2 larvae live in soil (pre-infective stage)
L3 larvae eaten + encyst in cecum (infective stage)
L4 larvae emerge (emergence = process of larval cyathostominosis - where it gets its name)
Evolve in L5 (egg-laying stage), migrate back to cecum + colon
L5 larvae feed superficially on intestinal mucosa causing disruption and typhlocolitis (inflammation of cecum/colon), which is further exacerbated by areas of local trauma from the remains of evacuated larval pits.
What is this?
Which endoparasite can cause obstruction in the intestines?
Ascariasis (Roundworm infection)
Ex. Toxacara canis
Which endoparasite can cause vascular compromise? How does it cause this? Which animal is this common in?
Strongylus vulgaris (bloodworm, large strongyle)
Mesenteric arteritis - Causes blockage of arterial blood supply and leads to infarction
Horse
What are the clinical signs associated with grass sickness? Which clinical sign is shown in this photo?
