Intestinal Pathology

Question 1

What are the three types of conditions that are associated with intestinal pathology?

Answer 1

Abdominal Pain
Acute Diarrhoea
Chronic Diarrhoea (+weight loss)

Question 2

What can cause abdominal pain?

Answer 2

• Torsion of the intestines
• Obstructions (internal or external)
• Rupture -which may be caused by the above

Question 3

What is the pathophysiological sequence of events involved with blockages/torsions of the intestines that eventually leads to necrosis?

Answer 3

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.

Question 4

What is the most common point of intussusception and why?

Answer 4

The ileoceacocolic junction/distal parts of the small intestine. This is because the SI is much more motile than the relatively fixed colon.

Question 5

How could a pedunculated lipoma lead to intestinal pathology?

Answer 5

This type of tumour often arises from mesenteric fat and has a stalk which can wrap round the intestine and cause an external obstruction.

Question 6

Compare and contrast the clinical signs associated with an upper GI obstruction and a lower GI obstruction.

Answer 6

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.

Question 7

What is the presentation of acute diarrhoea generally associated with?

Answer 7

Infectious diseases - especially when in young animals.

Question 8

What are the 5 basic mechanisms of diarrhoea formation?

Answer 8

Altered epithelial transport (secretory)
Altered structure/permiability
Osmotic effects
Altered motility
Damage to colonic mucosa. (more in hindgut fermenters)

Question 9

What parvovirus infects the cat?

Answer 9

Feline panleukopenia virus

Question 10

How does the type (aerobe vs. anearobe) of bacterial gut infection affect the type of lesions seen?

Answer 10

Aerobes - more focal/multifocal e.g. salmonella

Anearobes - diffuse e.g. clostrida

Question 11

What parasite of horses causes typical signs of pinprick lesions of the mucosa? What equivalent parasite is seen in farm animals?

Answer 11

Cyathostomins

Ostertagia

Question 12

What might be seen on microscopy in an animal infected with cryptosporiduim?

Answer 12

Crypotosporidia can be seen on the surface tips of intestinal villi and within the cells themselves.

Question 13

What are the consequences of acute diarrhoea?

Answer 13

Dehydration, heamoconcentration and hypovolaemic shock

Loss of ions - Na K HCO3 –> metabolic acidosis, hypokalaemia

Question 14

What are the common intestinal pathologies associated with chronic diarrhoea?

Answer 14

Chronic enterocolitis (IBD)
-lymphoplasmacellular
-eosinophilic
-granulomatous
Lymphangiectesia
Endoparasitism
Neoplasia
Grass sickness

Question 15

What parts of the GI tract are referred to by:

a) maldigestion
b) malabsorption

Answer 15

a) pancreas and liver

b) small intestine

Question 16

When is a protein losing enteropathy truly protein losing?

Answer 16

When the loss exceeds the ability of the liver to produce albumin.

Question 17

How does a protein losing enteropathy occur?

Answer 17

Changes leading to increased permeability –>loss of proteins
Chronic inflammation causes blockages that lead to reduced lymphatic drainage

Question 18

What is the appearance of intestinal villi that are affected by IBD?

Answer 18

Short and wide - infiltration of cells.

Question 19

What functional problems can arise from endoparasitism?

Answer 19

Malabsorption
Obstruction (e.g. ascarids)
Vessel blockage/compromise - large strongyles

Question 20

How is a neoplasia distinguished from an inflammatory infiltration?

Answer 20

Mitotic figures
Variation in types of cells (=normal as tumour would expect a single cell type)
Variation in cell size, appearance etc.

Question 21

What is grass sickness thought to be caused by?

Answer 21

Botulinum toxin damaging autonomic nervous system of the gut leading to halting of peristalsis.

Question 22

What is the presentation of the following forms of grass sickness:

a) acute disease
b) sub-acute/acute

Answer 22

a) nasogastric reflux, oesophageal ulceration, gastric dilation and rupture
b) weight loss, muscle tremors, rhinitis sicca, dysphagia, patchy sweating, constipation and large colon impaction

Question 23

How can intussusception be life threatening?

Answer 23

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)

Question 24

What animals, other than horses, can be affected by dysautonomia?

Answer 24

Cats and hares

Question 25

What tissues can FIP affect?

Answer 25

Serosal surfaces including peritoneum, pleura, pericardium and meninges.

Question 26

What does the synchronous emergence of cyathostomine larvae from the intestinal mucosa result in?

Answer 26

A protein losing enteropathy