L9: Ruminant Diarrheal GI Disease (Sanchez)

Question 1

Mechs of diarrhea

Answer 1

1) malabsorption (osmotic diarrhea)
2) hypersecretion
3) exudation (increased permeability)
4) Hypermotility

Question 2

Risk factors of diarrhea

Answer 2

1) host (low birth weight, prematurity, FPT)
2) environment (sanitation, pop. Density, feeding system)
3) agent (virulence, load)

Question 3

Most common reported causes of diarrhea in young and old ruminants

Answer 3

Young (30 days): salmonella, coccidia, rumen acidosis

Question 4

Dx of ruminant diarrhea

Answer 4

• etiology not essential for tx but useful in control/prevention strategies
• lab data:
• metabolic acidemia (HCO3 loss)
• hyponatremia, hypoCl, HyperK
• hypoglycemia
• CBC: hemoconcentration or leukopenia

Question 5

Enterotoxigenic E. Coli (ETEC): populations affected

Answer 5

-major cause of diarrhea in calves

Question 6

ETEC pathophys.

Answer 6

• encapsulated bacteria
• fimbrial antigen F5 allows attachment and colonization in distal SI (binds on immature epithelial cells)
• older calves: comorbidity can cause villous atrophy
• produces heat stable toxins which bind to endothelial receptors and cause hypersecretion of Cl, Na, H2O, and other electrolytes

Question 7

CS/labwork of ETEC

Answer 7

• watery diarrhea (rapid onset)
• not usually febrile
• hypothermic if in hypovolemic shock
• acidemia with decreased Na, Cl, K, glucose

Question 8

Dx/Tx/Prevent of ETEC

Answer 8

Dx: fecal PCR, ELISA
Tx: same for diarrhea in general
Prevent: give dry cows F5 vaccine, give oral F5 vaccine in outbreaks

Question 9

Attaching and Effacing E. Coli

Answer 9

EPEC: intimin gene
STEC: shiga-toxin producing
EHEC: both

• common in calves 2-21 days up to 4 months
• diarrhea can be bloody
• attachment in colon, SI, or both
• Dx: PCR

Question 10

Rotavirus general chars.

Answer 10

• most common viral cause of diarrhea*
• short incubation (12-24 hrs)
• stable in environment
• affects calves

Question 11

Rotavirus pathophys.

Answer 11

• small intestine
• malabsorptive diarrhea that causes villous atrophy but spares the crypts
• causes secretory diarrhea
• mixed infection with ETEC or Crypto is common
• morbidity high, mortality low to variable

Question 12

CS of rotavirus

Answer 12

• lethargy, dehydration
• anorexia
• low grade fever
• watery yellow diarrhea

Question 13

Dx of rotavirus

Answer 13

• electron microscopy (gold standard)
• PCR (high sensitivity, specificity)
• ELISA (fast, good agreement)

Question 14

Tx/Prevent of Rotavirus

Answer 14

• Tx: supportive
• Phenol-based disinfectants
• vaccination of dry cows
• oral calfhood vaccination (caution: can bind to colostral Ab)

Question 15

coronavirus most common at what age

Answer 15

2-24 days of age

Clinical course: 3-6 days

Question 16

Coronavirus implicated in what diseases?

Answer 16

Respiratory disease, winter dysentery

Question 17

Pathophys. Of coronavirus

Answer 17

• affects all SI, colon
• Colon: affects villi and crypts
• SI: affects villous enterocytes
• causes malabsorption and maldigestion
• more severe disease, higher mortality than rotavirus

Question 18

CS of coronavirus

Answer 18

Watery diarrhea +/- mucus

Severe lethargy

Question 19

Dx/Tx/Prevent of coronavirus

Answer 19

Dx: EM, ELISA; shedding drops quickly in course of dz

Tx/prevent same as for rotavirus

Question 20

Clostridium perfringens affects what age?

Question 21

Most common type of Clostridium perfringens

Answer 21

Type C

Question 22

CS of Clostridium perfringens

Answer 22

• Acute, hemorrhagic enteritis (typically fatal)
• bloody d, neuro signs
• Type A –> hemorrhagic abomasitis, abomasal ulceration

Question 23

Dx/Tx/prevent of C. Perfringens

Answer 23

Dx: Toxin ID. Type A can be normal flora

Tx: fluids, abx (penicillin), flunixin

Prevent: type C and D toxoid prior to calving. Antitoxin?

Question 24

Cryptosporidum affects what age?

Answer 24

C. Parvum:

Question 25

Most or 2nd most commonly isolated GI pathogen

Answer 25

Cryptosporidium

Question 26

Crypto morbidity/mortality?

Answer 26

High morbidity, low mortality -not host specific

Question 27

Pathophys. Of crypto

Answer 27

- oocysts excyst following exposure to gastric acid and bile salts - sporozoites infect enterocytes from abomasum to colon but mostly in the SI - infective oocytes passed in feces - villous atrophy, fusion, crypt hyperplasia and inflammation --> malabsorptive diarrhea

Question 28

Peak shedding age of cryptospordium

Answer 28

- 7-14 days (up to 1 month) | - CS usually 7 days (single infections)

Question 29

CS of crypto

Answer 29

-diarrhea, decreased appetite, dehydration

Question 30

Morbidity of crypto

Answer 30

Up to 100% of dairy calves, less than 5% of beef calves

Question 31

Dx/Tx of crypto

Answer 31

- floatation, direct exam, acid-fast stain - PCR, ELISA: variable sensitivity/specificity Tx: supportive only

Question 32

Prevent of crypto

Answer 32

- highly resistant organism - practical disinfectant not available - environmental hygeine: calf hutches, separate feeding supplies for calves

Question 33

2 main causes of Salmonellosis

Answer 33

1) Salmonella enterical serovar Typhimurium | 2) " " serovar Dublin

Question 34

Pathophys. Of salmonellosis

Answer 34

- fecal-oral transmission predominates (also URT and conjunctiva) - invasion through M-cells, enterocytes, tonsilar lymphoid tissue and dissemination through mononuclear cells - distal SI, cecum, colon affected: -causes hemorrhage, necrosis, mesenteric lymphadenopathy, pseudomembrane formation, and fibrin plugs in GB

Question 35

Age most affected by salmonellosis

Answer 35

1-4 months (as early as 3 days)

Question 36

CS and lab findings in Salmonellosis

Answer 36

CS: diarrhea +/- blood or mucus, fever, lethargy, ill thrift Lab: hypoproteinemia, neutropenia w/ toxicity if acute, leukocytosis if chronic High morbidity/mortality in outbreaks

Question 37

Dx/Tx/prevent of Salmonellosis

Answer 37

Dx: fecal culture, PCR Tx: supportive, abx, NSAIDs Prevent: environmental hygiene, biosecurity, colostrum management, +/- vaccines

Question 38

Salmonellosis risk factors

Answer 38

- prophylactic antimicrobial use - co-use of maternity, hospital pens - open herds

Question 39

Importance of neonatal diarrhea

Answer 39

#1 cause of neonatal death -difficult to control/treat >$120 mil/year economic impact