Bovine Flashcards
What type of virus is BVD - bovine viral diarrhea
Pestivirus, flaviviridae - RNA virus
Why is it significant that BVD is an RNA virus
It can reassert and change, escaping immune mechanisms, remaining active
What are 3 major things /effects that have been attributed to BVD
Loss of productivity , reproductive wastage, increased morbidity and mortality
How can the RNA vins (bvd) be classified
Type 1 - cytopathic
Type 2 - non cytopathic
Does biotype of a virus indicate violence
No - just now the tissue behaves in tissue culture
What ave the 5 clinical forms of BVD
Subclinical, acute, hemorrhagic syndrome, reproductive loss and mucosal disease/ chronic
Describe subclinical BVD
Animal has antibodies present but has not been observed to have signs
Describe acute BVD - when is it most likely to occur , what is the incubation period and what signs do you see
Mostly in cattle 6 - 24 months old, after incubation for. 5-7 days, causes fever, leukopenia, anorexia, oculonasal discharge, oral erosions, ulcers and diarrhea
In acute bvd, what organs or organ systems are most affected
Damages the epithelium of the mouth, esophagus, intestine and bronchi
How can bacterial pathogens play a role in acute bvd
Can lead to immunosuppresion and pneumonia
Describe the hemorrhagic syndrome form of BVD
BVD virus induced thrombocytopenia (decreased platelets)
How does BVD affect reproduction in cattle
Infertility and early embryonic death, abortion - can occur at any stage of gestation
Infection by what virus at day 100 - 150 of gestation most commonly leads to congenital defects like hydrocephalus, cerebellar hypoplasia , ocular defects, hupomyelinogenesis, etc
BVD
How can you get a calf who is persistent infected with BVD
If the calf is infected between days 40 - 125 of gestation and was exposed to the non cytopathic bio type
What is the main way BVD is maintained in a herd
Pi infected calves - act as reservoirs and consistently shed the virus (calf is immunocompetent)
Describe mucosal disease (due to bvd) and chronic BVD
When a pi animal is super infected with the cytopathic biotype or the non cytopathic switches to the cytopathic type - mucosal disease is a peracute often fatal attack of bvd and chronic BVD is eventually fatal
How can you diagnose BVD
Through antigen detection - either with fluorescent antibodies , immuno histochemistry, or antigen ELISA, can also use PCRor serology
How can uw detect carriers of BVD
Ear notches for IHC
What is the most common treatment for BVD
Prevention of secondary infections (like Mannheima hemolytica) and providing fluids and electrolytes
What are the principle means of preventing and controlling BVD
Biosecurity, vaccination and detecting/ eliminating carriers of pi animals
How many doses are required for killed vaccines? Modified live virus vaccines?
2 for killed, one for MLV
When are replacement heifers vaccinated for BVD
5-6 months old with a MLV
When are cows vaccinated for BVD
Prior to breeding season bing a MLV with both biotypes 1 and 2 - cytophathic and non cytopathic
Can you vaccinate pregnant cows with MLV or killed vaccines for bvd
Safe to vaccinate with the killed vaccine - fetal protection better when MLV are used