Unit 3 - GI Lecture 4

Question 1

What are the consequences of atrophic enteritis?

Answer 1

1. Markedly reduced surface area for digestion and absorption
2. Villi are covered by immature cells with less digestive and absorptive capabilities

Question 2

What does mechanism A of atrophic enteritis target?

Answer 2

superficial villus epithelial cells

Question 3

What does mechanism B of atrophic enteritis target?

Answer 3

dividing crypt epithelial cells

Question 4

What viruses use mechanism A of atrophic enteritis?

Answer 4

Rotavirus, Coronavirus (dogs, pigs), Coccidia (swine), Enteroinvasive bacteria (Salmonells, SEEC, E. Coli)

Question 5

What agents use mechanism B of atrophic enteritis?

Answer 5

Parvovirus (cats, dogs), radiation, chemotheraputic agents

Question 6

What agents use a combination of mechanisms A and B of atrophic enteritis?

Answer 6

Coccidia (bovine, Coronavirus (bovine), BVD (bovine)

Question 7

What necropsy findings are associated with atrophic enteritis?

Answer 7

maldigestion, malabsorption, thin-walled intestine, watery diarrhea, mesenteric lymph nodes not typically enlarged

Question 8

In the case of canine parvovirus, near complete loss of villus epithelial cells results in what?

Answer 8

an inability to digest and absorb, loss of mucosal integrity, and prolonged recovery

Question 9

What is secretory diarrhea?

Answer 9

when pathogens produce toxins which result in increased active secretion

Question 10

What is the pathogenesis of secretory diarrhea?

Answer 10

1. Pathogenic strain attaches to villus epithelial cells by pili
2. Pathogenic strain proliferates
3. Release enterotoxins which increase intestinal secretion by altering electrolyte and water movement across the plasma membrane
4. Secretory diarrhea

Question 11

What necropsy/clinical findings are associated with secretory diarrhea?

Answer 11

watery diarrhea, rapid dehydration and death, mesenteric lymph nodes not typically enlarged, will have chyle in the lacteals

Question 12

When does increased vascular permeability occur?

Answer 12

with inflammation of the intestinal mucosa

Question 13

What is the pathogenesis of increased vascular permeability?

Answer 13

1. Inflammation
2. Release of inflammatory mediators
3. vessel dilation
4. Leakage of fluid and plasma proteins from vessels

Question 14

In chronic cases if increased vascular permeability what can happen?

Answer 14

1. Exudate continually seeps from the mucosal surface into the gut lumen
2. Significant amount of plasma protein can be lost
3. Panhypoproteinemia (protein losing enteropathy)

Question 15

What is one function of the colon?

Answer 15

to reduce the volume of water and electrolytes lost in feces

Question 16

What disorders in the colon causes diarrhea?

Answer 16

resorptive capacity surpassed due to increased fluid from the small intestine or resorptive functional capacity reduced

Question 17

If there is a mild increase in fluid from the small intestine how does the colon respond and what is the clinical outcome?

Answer 17

the colon compensates by removing fluid from the colon and there is normal feces but decreased weight gain

Question 18

If there is a marked increase in fluid volume from the small intestine how does the colon respond and what is the clinical outcome?

Answer 18

incomplete or colon compensation to remove fluid causing small bowel diarrhea

Question 19

If thee is normal fluid volume in the small intestine and decreased fluid volume removed by the colon what is the clinical outcome?

Answer 19

large bowel diarrhea

Question 20

If there is a marked increase in fluid volume from the small intestine and a decrease in fluid removal by the colon what is the clinical outcome?

Answer 20

explosive diarrhea

Question 21

What is large bowel diarrhea due to?

Answer 21

the reduced capacity to absorb fluid and electrolytes presented from the small intestine

Question 22

Describe the appearance of large bowel diarrhea.

Answer 22

frequent passage of small amounts of fluid feces occasionally with fresh mucus and undigested blood

Question 23

What are the major diarrheal diseases of domestic species?

Answer 23

lymphangiectasia, immune mediated, or infectious

Question 24

What is lymphangiectasia?

Answer 24

a pathologic dilation of lymph vessels

Question 25

What is lymphangiectasia general caused by?

Answer 25

a process which puts back pressure on the lymph vessels leading them to dilate

Question 26

What are the specific causes of intestinal lymphangiectasia?

Answer 26

lymphoma, a mesenteric lymphadenitis, peritonitis, inflammatory bowel disease (IBD)

Question 27

What does intestinal lymphangiectasia result in?

Answer 27

malabsorption (especially of fats), rupture of lymphatics causing protein loss, chronic diarrhea, wasting, and hypoproteinemia

Question 28

What can hypoproteinemia lead to?

Answer 28

edema, ascites, and hydrothorax

Question 29

What lesions are associated with intestinal lymphangiectasia?

Answer 29

distension of villus lacteals often accompanied by distension of submucosal, serosal, and mesenteric lymphatics

Question 30

What is inflammatory bowel disease characterized by?

Answer 30

an infiltrate of inflammatory cells in the intestinal lamina propria

Question 31

What is IBD an idiopathic and common cause of?

Answer 31

diarrhea and vomiting in both dogs and cats

Question 32

What clinical signs are associated with inflammatory bowel disease?

Answer 32

diarrhea (chronic or intermittent), +/- vomiting, and weight loss

Question 33

What does IBD result from?

Answer 33

a complex interaction between host genetics, the intestinal microenvironment, and the immune system

Question 34

How do immmunological mechanisms lead to IBD?

Answer 34

it is believed to result from an inappropriate immune response to dietary antigens and/or commensal microbial flora

Question 35

What does ETEC stand for?

Answer 35

enterotoxigenic E. coli

Question 36

What does AEEC stand for?

Answer 36

attaching-effacing E. coli

Question 37

What species does ETEC commonly affect?

Answer 37

PIGS, calves, and lambs

Question 38

What is the mechanism of ETEC?

Answer 38

1. Attach 2. Proliferate 3. Release toxins 4. Secretory diarrhea

Question 39

Where does ETEC localize?

Answer 39

the small intestine

Question 40

What species does AEEC commonly affect?

Answer 40

pigs, rabbits, lambs, dogs, calves, +/- cats

Question 41

What is the mechanism of AEEC?

Answer 41

1. Bacteria attach to enterocytes by a non-pillus adhesion factor 2. Efface epithelial brush border and cause detachment and destruction of absorptive cells 3. villus atrophy 4. Malabsorption/maldigestion

Question 42

Where does AEEC localize?

Answer 42

intestine and colon

Question 43

What supportive evidence is needed to diagnose an E. coli infection?

Answer 43

culture of a heavy and relative pure population of a pathogenic colonoy type, histiologic evidence of villus colonization or attaching/effacing lesions, pathogenic genotype

Question 44

Clostridium perfringens causes enteric disease as a result of the _________ ___ _______.

Answer 44

elaboration of toxins

Question 45

What conditions that may provide C. perfringens an opportunity to overgrow and cause disease?

Answer 45

1. A diet with excess protein and carbohydrate 2. Abrupt feed changes that disturb the normal intestinal flora 3. An insult oF the small intestinal mucosa leading to maldigestion/malabsorption

Question 46

Clostridium perfringens type C is an important cause of what?

Answer 46

hemorrhagic and necrotixing enteritis in several species

Question 47

What are the commonly affected species by Clostridium perfringens type C?

Answer 47

pigs, calves, foals, sheep, and goats

Question 48

What is the signalment for a Clostridium perfringens type C infection?

Answer 48

most typically observed in the first week of life or following a dramatic dietary change

Question 49

What clinical signs are associated with a Clostridium perfringens type C infection?

Answer 49

hemorrhagic diarrhea and rapid death, animal may be found dead with no prior clinical signs

Question 50

Where are lesions associated with a Clostridium perfringens type C infection typically located?

Answer 50

small intestine typically the jejunum

Question 51

What type of lesion is associated with a Clostridium perfringens type C infection?

Answer 51

fibrinonecrotic and hemorrhagic enteritis +/- emphysema of the intestinal wall and segmental necrotic enteritis

Question 52

What Clostridium perfringens type C toxin is in charge of the lesions associated with the infection?

Answer 52

beta toxin

Question 53

What does histopath typically look like in animals with a Clostridium perfringens type C infection?

Answer 53

necrotic intestinal villi are covered by numerous, large, gram-positive bacilli

Question 54

What should you use to diagnose a Clostridium perfringens type C infection?

Answer 54

gross lesions, histopath, gram-stained mucosal scraping, bacterial culture

Question 55

What is the pathogenesis of necrotic enteritis due to coccidiosis?

Answer 55

1. Coccidiosis 2. malabsorption/maldigestion 3. C. perfringens proliferates on the unabsorbed ingesta 4. releases toxins 5. necrotic enteritis