Bovine virus diarrhea and pi s
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Bovine Virus Diarrhea and PI’s. Brendan Kraus, DVM Spur Ridge Vet Hospital Marion, KS. What is BVD?. Bovine Virus Diarrhea 2 Biotypes & 2 Genotypes A contagious disease transmitted in bodily fluids Causes a wide range of clinical symptoms Cause marked suppression of immune system.

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Bovine virus diarrhea and pi s

Bovine Virus Diarrhea and PI’s

Brendan Kraus, DVM

Spur Ridge Vet Hospital

Marion, KS


What is bvd
What is BVD?

  • Bovine Virus Diarrhea

  • 2 Biotypes & 2 Genotypes

  • A contagious disease transmitted in bodily fluids

  • Causes a wide range of clinical symptoms

  • Cause marked suppression of immune system


Biotypes of bvd type does not affect immune response

Cytopathic

Kills cells in tissue culture

Arises from a virus mutation

Most common strain in vaccines

Noncytopathic

Does not change culture cells

Most common biotype found in nature

Biotypes of BVD(Type does not affect immune response!)


Genotypes of bvd

Type 1

Original strains of BVD that were isolated

Is included in all BVD vaccines

*There is some cross protection with vaccines between types 1 & 2

Type 2

This type was more recently discovered

Hemorrhagic syndrome strains

Is included in most BVD vaccines now

Genotypes of BVD


Bvd symptoms

70-90% of infections are subclinical

Pneumonia

Fever

Rhinitis

Diarrhea

Oral and GI ulcers

Immune suppression

Abortions

Stillborns

Birth Defects

BVD symptoms



What is p ersistent i nfection
What is Persistent Infection?

  • A PI calf is born infected with the virus

    • This can happen if the dam is a PI animal

    • This can happen if the dam is transiently infected during pregnancy from another animal

    • *The virus must be non-cytopathic*

  • The calf must be infected between 40-100 days approximately

    • During this time the calf has no immune system so it recognizes the virus as “self” and never clears it

    • After this time, the calf’s immune system is developed enough to fight the virus


Manifestations of calves infected in utero

PI calf (Body does not recognize virus)

Virus is always circulating in body

May die soon after birth

Many are clinically normal

This is the natural reservoir of the virus

Infected in utero but not PI (infected around or after day 100)

Congential defects

Skeletal problems

Dome shaped head

Shortened lower jaw

Eye abnormalities

Brain defects

Abortions

Clinically normal calves

Calves that are not killed can clear the virus and go on

Manifestations of Calves infected in utero


Pi calves
PI Calves

  • PI calves are more likely to die than non-PI calves in the first year

    • Pneumonia

    • Diarrhea

    • Poor doer

    • Many look and perform like a healthy calf



Mucosal disease
Mucosal Disease

  • This is Highly fatal syndrome in which the mucous membranes become ulcerated

    • Mouth

    • Stomach

    • Intestine

    • Teats

    • Coronary bands of hooves



Mucosal dz cont
Mucosal Dz, cont

  • For mucosal disease to occur a PI calf (noncytopathic) must be superinfected with a cytopathic strain.

    • The more closely related the viruses are genetically, the worse the disease

    • When a noncytopathic virus found in nature mutates to cytopathic & the calf is exposed

    • When the PI calf’s own noncytopathic strain mutates


Pi calf shedding
PI Calf Shedding

  • PI calves shed the virus their entire life

    • Some periods they may shed a lot, and others not as much

    • Virus shed in saliva, tears, urine, feces, blood

    • There is so much virus shed, that most vaccines cannot protect other cattle against a PI

    • Continue to infect cow herds and create more PI’s


Pi diagnosis
PI Diagnosis

  • Ear Notch Elisa

  • Ear Notch Immunohistochemisty

  • Polymerase Chain Reaction

  • Virus Isolation

    These tests can be done at anytime in a PI’s life and only need to be done once. If positive, will always be positive. If negative, can be infected with BVD but will not be a PI

    If transiently infected, some tests may be positive, but the calf may need to be tested again in a month to confirm PI status


Bvd control prevention
BVD Control& Prevention

  • Vaccination with a vaccine using Type 1 and Type 2 strains

  • Modified live vaccine creates a stronger, more natural immunity, is cheaper, and less doses required

  • Newer vaccines have label claims that if given to cow pre-breeding can successfully prevent PI in fetus


Bvd control prevention cont
BVD Control & Prevention, cont.

  • Test herds for PI calves and remove all animals to quarantine**

    • Test all dams of PI calves to see if they are also PI

  • Test all purchased breeding animals before entry into herd