Intestinal Pathology Flashcards
How long does it take for the cell population of the gut to turn over?
3–5 days
How does inflammatory infiltrate of the lamina propria affect the level of absorption?
Decreased SA, reduced absorption
What are the clinical signs associated with intestinal dysfunction?
Abdominal pain
V+
Diarrhoea - acute and chronic
Constipation
What types of displacement of the intestine can cause abdominal pain?
Volvulus
Torsion
What is the difference between torsion and volvulus?
Torsion - twisting on long axis
Volvulus - twisting on mesenteric axis
What types of obstruction are there?
Internal and external
Give examples of an internal obstruction
FB
Parasites
Tumour
Intussusception
Give an example of an external obstruction
Strangulating lipoma
What is the most common type of intestinal displacement?
Volvulus
Where in horses is torsion common?
Free end of the left colon
What vessels get compressed first in volvulus/torsion/intussuception?
Thin walled veins
How does a volvulus/torsion/intussuception result in peritonitis?
Veins get compressed Venous congestion Ischaemic infarction Necrosis Reduced gut barrier function - bacteria in and endotoxaemia (if G-) Proximal obstruction Perforation - gut contents into abdo PERITONITIS
What clinical presentation would you associate with an upper intestinal tract obstruction?
ACUTE AND SEVERE
Vomiting
Metabolic alkalosis
Dehydration
Reduced renal flow and uraemia
What clinical presentation would you associate with lower GI tract obstruction?
LESS ACUTE THAN UGIT
- increased fluid resorption proximal to the obstruction - less vomiting
- pressure - ulceration and infarction +/- perforation
- eventually haemorrage and peritonitis
Eventual metabolic acidosis due to dehydration + catabolism of fat+muscle - ketones
What is the difference between fibrin and fibrinous tissue?
Fibrin - soft, yellow, stringy
Fibrinous tissue - scar tissue - firm, white
What are the four mechanisms of diarrhoeal pathogenesis?
- Altered structure/permeability (malabsorption)
- Altered epithelial cell transport (secretory diarrhoea)
- Osmotic effects (e.g. maldigestion)
- Altered motility
How can osmotic effects result in diarrhoea ?
Give an example
Lactose Intolerance
Increased solutes in gut lumen therefore water moves out
What bacteria causes a secretory diarrhoea?
E.Coli
Chloride ions into gut lumen
What are the broad consequences of acute diarrhoea?
Loss of water
Loss of ions
How does acute loss of water affect the patient?
Dehydration
Haemoconcentration
Hypovolaemic shock
How does acute loss of ions affect the patient?
What ions are typically lost?
Sodium, Potassium, Bicarbonate
Hypokalaemia
Metabolic acidosis
What viruses can cause acute diarrhoea?
Rotavirus
Coronavirus
Parvovirus
What bacteria can cause acute diarrhoea?
C. Diff
Campylobacter
Salmonella
What Protozoa can cause acute diarrhoea?
Coccidia
Cryptosporidium
What endoparasites can cause acute diarrhoea?
CYATHOSTOMES (horses principally)
What pathogens target the tips of villi?
CRYPTOSPORIDIUM
E.COLI
How could you identify cryposporidium on histology?
Oocysts (dots) seen on tips of villi - adhering to brush border
What pathogen attacks intestinal crypt cells?
Why?
What other cell type does it attack?
PARVO
Needs DNA polymerase therefore needs rapidly dividing cells
Immune cells
How does rotavirus affect villi?
Attacks enterocytes towards the tips of villi
Villi become blunted, stunted and fused
Loss of epithelium
What appearance of the intestine is pathognomonic of Parvo?
Payer’s patches ‘punched out’
+crypts with necrotic cells on histology
What types of lesions are associated with salmonellosis?
Necrotising + Ulcerative lesions - fibrino-necrotising
severe focal or multi focal mucosal damage
ILIOTIFLOCOLITIS
What causes ‘colitis X’?
Clostridial colitis
Toxins released into gut lumen cause diffuse reddening
What is seen in the colon of horses with cyathostominosis?
Red dots within mucosa (encysted L3/4 larvae)
What can cause chronic diarrhoea +/- weight loss?
Chronic enterocolitis (IBD)
- lymphoplasmacytic
- eosinophilic
- granulomatous
Lymphangiectasia
Endoparasites
Neoplasia
Grass sickness
How can IBD be subdivided histologically?
- Lymphoplasmocytic
- eosinophilic
What can cause protein losing enteropathy?
- increased permeability to plasma proteins - lost to intestinal lumen
- chronic inflammation - lymphatic blockage
How can PLE result in oedema and ascites?
What other clinical sign might be associated with this?
Albumin lost Loss exceeds liver synthesis Hypoalbuminaemia Decreased plasma osmotic pressure Oedema and ascites
Wasting and emaciation
How can bacterial overgrowth result in malabsorption?
Toxins - intestinal epithelial cell injury
Consumption of nutrients
Bile salt deconjigation and subsequent deficiency.
What neoplastic condition can cause a secondary PLE?
Intestinal lymphoma
What does fibrin education of a granulomatous lesion indicate?
Chronic active lesion
How could you describe exaggerated folding of the intestinal mucosa (granulomatous enteritis)?
Cerebroform
When might you expect to see a giant, multinucleated cell in the intestines in a cow with diarrhoea ?
Johnes
What endoparasite is associated with malabsorption?
Cyathostomins
What endoparasite is associated with obstruction?
Ascarids
What endoparasite is associated with vascular compromise?
large strongyles
E.g. strongylus vulgaris in horses
What endoparasite can cause mesenteric arteritis in horses?
How does this affect the gut?
Strongylus vulgaris
necrosis
What can be seen histologically in horses with acute grass sickness?
Dark (pyknotic) small, marginalised nucleus of neurones in e.g. submucosa plexus
Decreased number, hypereosinophilic
What is the acute presentation of grass sickness?
Nasogastric reflux and oesophageal ulceration
Gastric dilation and rupture
What is the subacute/chronic presentation of grass sickness?
Weight loss Muscle tremors Rhinitis Sicca (dry nose) Dysphagia Patchy sweating Constipation Large colon impaction
