Intestinal Pathology Flashcards
What are the three types of conditions that are associated with intestinal pathology?
Abdominal Pain Acute Diarrhoea Chronic Diarrhoea (+weight loss)
What can cause abdominal pain?
- Torsion of the intestines
- Obstructions (internal or external)
- Rupture -which may be caused by the above
What is the pathophysiological sequence of events involved with blockages/torsions of the intestines that eventually leads to necrosis?
Initially the tissues are compressed and thinner blood vessels, which are the veins, collapse. Arteries are still open so their is an influx of blood leading to swelling. Eventually the swelling becomes so severe that arterial walls also collapse leading to infarction and necrosis of the intestine.
What is the most common point of intussusception and why?
The ileoceacocolic junction/distal parts of the small intestine. This is because the SI is much more motile than the relatively fixed colon.
How could a pedunculated lipoma lead to intestinal pathology?
This type of tumour often arises from mesenteric fat and has a stalk which can wrap round the intestine and cause an external obstruction.
Compare and contrast the clinical signs associated with an upper GI obstruction and a lower GI obstruction.
Upper - more severe and acute. Gas and fluid accumulate proximal to the obstruction so cause vomiting which leads to metabolic acidosis (loss of acid), dehydration and reduced renal flow+uraemia.
Lower - generally less acute and more intermittent. Pressure from fluid and gas can lead to ulceration and infarction and then haemorrhage and peritonitis. Metabolic ALKylosis more likely as catabolism of muscle and fat produces keto bodies.
What is the presentation of acute diarrhoea generally associated with?
Infectious diseases - especially when in young animals.
What are the 5 basic mechanisms of diarrhoea formation?
Altered epithelial transport (secretory) Altered structure/permiability Osmotic effects Altered motility Damage to colonic mucosa. (more in hindgut fermenters)
What parvovirus infects the cat?
Feline panleukopenia virus
How does the type (aerobe vs. anearobe) of bacterial gut infection affect the type of lesions seen?
Aerobes - more focal/multifocal e.g. salmonella
Anearobes - diffuse e.g. clostrida
What parasite of horses causes typical signs of pinprick lesions of the mucosa? What equivalent parasite is seen in farm animals?
Cyathostomins
Ostertagia
What might be seen on microscopy in an animal infected with cryptosporiduim?
Crypotosporidia can be seen on the surface tips of intestinal villi and within the cells themselves.
What are the consequences of acute diarrhoea?
Dehydration, heamoconcentration and hypovolaemic shock
Loss of ions - Na K HCO3 –> metabolic acidosis, hypokalaemia
What are the common intestinal pathologies associated with chronic diarrhoea?
Chronic enterocolitis (IBD) -lymphoplasmacellular -eosinophilic -granulomatous Lymphangiectesia Endoparasitism Neoplasia Grass sickness
What parts of the GI tract are referred to by:
a) maldigestion
b) malabsorption
a) pancreas and liver
b) small intestine
When is a protein losing enteropathy truly protein losing?
When the loss exceeds the ability of the liver to produce albumin.
How does a protein losing enteropathy occur?
Changes leading to increased permeability –>loss of proteins
Chronic inflammation causes blockages that lead to reduced lymphatic drainage
What is the appearance of intestinal villi that are affected by IBD?
Short and wide - infiltration of cells.
What functional problems can arise from endoparasitism?
Malabsorption
Obstruction (e.g. ascarids)
Vessel blockage/compromise - large strongyles
How is a neoplasia distinguished from an inflammatory infiltration?
Mitotic figures
Variation in types of cells (=normal as tumour would expect a single cell type)
Variation in cell size, appearance etc.
What is grass sickness thought to be caused by?
Botulinum toxin damaging autonomic nervous system of the gut leading to halting of peristalsis.
What is the presentation of the following forms of grass sickness:
a) acute disease
b) sub-acute/acute
a) nasogastric reflux, oesophageal ulceration, gastric dilation and rupture
b) weight loss, muscle tremors, rhinitis sicca, dysphagia, patchy sweating, constipation and large colon impaction
How can intussusception be life threatening?
Mesentry can be drawn into the telescoping part which leads to pressure on the messenteric vessels causing them to become occluded. (Thin walled veins occluded first)
What animals, other than horses, can be affected by dysautonomia?
Cats and hares
What tissues can FIP affect?
Serosal surfaces including peritoneum, pleura, pericardium and meninges.
What does the synchronous emergence of cyathostomine larvae from the intestinal mucosa result in?
A protein losing enteropathy
