Lecture 8

Question 1

BVD Transmission

Answer 1

direct contact
-mainly through shedding in saliva, mucus, semen and manure
can be spread vertically
-transplacental

Question 2

BVD mainly infects?

Answer 2

young, stressed or unvaccinated animals

Question 3

BVD sites of virus replication in the body

Answer 3

upper respiratory and lymphoid tissues

Question 4

BVD virus attacks?

Answer 4

rapidly dividing cells such as

• lymphoid tissue
• enterocytes
• sin cells of mouth

Question 5

Clinical sings of BVD

Answer 5

inapparent
-no signs 
-70-90%
-shed for 2 weeks
non-specifc
-fever
-decreased production
-decreased appetite
failure to catch, abort
calves
-small
-neurological defect
-PIs
pneumonia 
diarrhea
mouth ulcers

Question 6

Non-cytopathic

Answer 6

• doesn’t kill culture cells when inoculated on them
• very common
• often found by itself
• can cross the placenta

Question 7

Cytopathic

Answer 7

• kills culture cells
• rare
• almost always accompanied by non-cytopathic biotype
• cannot cross the placenta

Question 8

Critical period for BVD

Answer 8

42-125

Question 9

When is calf’s immune system strong enough in utero to fend off virus?

Answer 9

170-280 days

Question 10

Mucosal disease

Answer 10

PI animals only, usually

Question 11

Clinical signs of mucosal disease

Answer 11

fever
oral erosions
diarrhea sometimes with blood
die in 5-7 days

Question 12

Risk factors for BVD

Answer 12

herd has history of inadequate immunization

animals are purchased and screening test not preformed

Question 13

BVD treatment

Answer 13

no specific treatment

Question 14

Critical Control Point to prevent PI

Answer 14

• correct vaccination program
• MLV for fetal protection
• no nose-to-nose of manger/water contact for 3 weeks
• test for BVD-PI in quarantine
• vaccinate purchases in quarantine

Question 15

Salmonellosis depends on?

Answer 15

infectious dose
immunity of host
virulence of the strain of bacteria

Question 16

Clinical signs of salmonellosis

Answer 16

diarrhea
-bloody, fibrin casts
fever, off-feed
drop in milk 
abortions

Question 17

Reasons for Salmonella outbreaks

Answer 17

-resevoir hosts
-easily contaminates and multiplies in feed
-carriers
5% healthy cows shed, 20% of sick culls shed
nature of manure

Question 18

Johne’s disease affects?

Answer 18

the ileum

Question 19

Transmission of Johne’s

Answer 19

fecal oral

-advance stages may pass from dam to fetus in utero or in colostrum

Question 20

Pathology of Johne’s disease

Answer 20

bacteria multiply in the intestinal wall
attract inflammatory cells to site which cause thickening and ulceration
-protein is not absorbed in diet and is lost through inflamed intestinal walls