Lecture 8 Flashcards
BVD Transmission
direct contact
-mainly through shedding in saliva, mucus, semen and manure
can be spread vertically
-transplacental
BVD mainly infects?
young, stressed or unvaccinated animals
BVD sites of virus replication in the body
upper respiratory and lymphoid tissues
BVD virus attacks?
rapidly dividing cells such as
- lymphoid tissue
- enterocytes
- sin cells of mouth
Clinical sings of BVD
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
Non-cytopathic
- doesn’t kill culture cells when inoculated on them
- very common
- often found by itself
- can cross the placenta
Cytopathic
- kills culture cells
- rare
- almost always accompanied by non-cytopathic biotype
- cannot cross the placenta
Critical period for BVD
42-125
When is calf’s immune system strong enough in utero to fend off virus?
170-280 days
Mucosal disease
PI animals only, usually
Clinical signs of mucosal disease
fever
oral erosions
diarrhea sometimes with blood
die in 5-7 days
Risk factors for BVD
herd has history of inadequate immunization
animals are purchased and screening test not preformed
BVD treatment
no specific treatment
Critical Control Point to prevent PI
- 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
Salmonellosis depends on?
infectious dose
immunity of host
virulence of the strain of bacteria
Clinical signs of salmonellosis
diarrhea -bloody, fibrin casts fever, off-feed drop in milk abortions
Reasons for Salmonella outbreaks
-resevoir hosts
-easily contaminates and multiplies in feed
-carriers
5% healthy cows shed, 20% of sick culls shed
nature of manure
Johne’s disease affects?
the ileum
Transmission of Johne’s
fecal oral
-advance stages may pass from dam to fetus in utero or in colostrum
Pathology of Johne’s disease
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
