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Bovine Viral Diarrhoea Virus (BVDV) - Coggle Diagram
Bovine Viral Diarrhoea Virus (BVDV)
transmission
contact with infected cattle
sexually transmitted
test before entering AI studs and essential for all purchased bulls prior to their use on farm
placenta cow->calf
if infected in-utero they are born permanently and persistently infected with the virus
will excrete large vol. of virus whole lives and main route of infections in other animals
significant risk factors
Direct contact with cattle from a neighbouring, infected herd
Contact with other cloven hooved animals (sheep, deer, pigs)
Contact with infected materials, such as equipment, boots or clothing, other visitors
PI bulls can excrete virus in their semen
There is experimental evidence to suggest that biting flies may also be able to spread BVD
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BVD is a virus and lasts for approximately 3-4 weeks in the environment.
1-2 weeks outside and up to 4 weeks in damp buildings
destroyed by sunlight, drying, temperature extreme, disinfectants and pH
clinical signs
cattle show few clinical signs and produce protective antibodies 3-4 weeks
May temporarily lower immunity to other infectious diseases esp, young calves
salmonellosis
respiratory infections
coccidiosis
diarrhoea
not
often seen
if infection during
early pregnancy
embryonic death
return to oestrus
foetal death/abortion
mummification of feotus
birth defects of the nervous system and eyes
weak/premature calves
live persistently infected calves
if infection
before 110/120 days of pregnancy
--> birth of a live, but persistently infected calf.
failure of developing immune system of foetus to function properly before 110 days
PI animals fail to thrive
noticeably smaller than age cohort
brain and eye defects e.g. blind, lack coordination
cull for welfare reasons as well as being a source of infection
if acute infection is seen in a naive herd then abortion, infertility and mild signs such as pyrexia and diarrhoea will be seen
mucosal disease
when persistently infected animals become super infected with cytopathic BVD virus
most commonly seen in
6-12 month old
calves
clinical signs - sudden onset
depression
fever
anorexia
excess salivation
ulcers on mouth and muzzle
purulent discharges from eyes and nostrils
profuse diarrhoea with shreds of gut mucosa and blood during the terminal stages
rapid weight loss followed by death within 5-10 days
Diagnosis
serology
exposure to virus
active infection can be diagnosed by PCR based tests
samples
blood
hair plucks
skin biopsies
The current eradication schemes in the UK use skin plugs created when juvenile animals are ear tagged for identification for detection of PI animals.
Colostrum intake can mask the detection of PI as maternal antibodies will be in the blood for 3 – 4 months and these can hinder the normal diagnostic assays.
treatment
acute BVD
treat any concurrent infections if present
NSAIDs and fluids
persistent infection
e.g. has been treated several times for digestive/respiratory infections
cull PI animals ASAP (not poss to clear the virus and they are super spreaders)
mucosal disease in PI animals always fatal
always cull, no treatment
biosecurity and vaccination
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Closed herd (If practical)
Quarantine all incoming animals, if not closed, for 4 weeks with appropriate testing regime
Avoid nose to nose contact with neighbours and use double fencing 3 m apart
Regular monitoring
Vaccination if none of the above are possible (but this limits monitoring)
Avoid grazing cattle with sheep