Bovine Viral Diarrhea Virus Persistent Infection (BVD-PI) Ear Notch Testing
Program for Cattle Herds
Bovine Virus Diarrhea Virus (BVDV) infection in cattle herds can
result in major economic loss from poor reproductive performance
(reduced percent pregnant, increased abortion and stillbirth) or poor
calf performance (increased calf sickness and death loss). Cattle
persistently infected with BVDV (BVD-PI) are the primary reservoir for
BVDV infection in cattle herds, and thus are the major focus of control
NEW: Jan 08
and Eradication Program (BVDCEP)
The Washington Animal Disease Diagnostic Laboratory (WADDL) at
Washington State University is implementing a “BVD-PI Ear Notch Testing
Program” designed for whole herd testing to aid cattle producers in
identification and removal of BVD-PI animals. The testing program is
based on the most current information available. However, herds should
be examined on a case-by-case basis as whole herd testing may not be
warranted in some situations.
Which animals to sample?
- All calves born alive. Testing and removal of BVD-PI calves must
occur before exposure of females in the breeding herd to bulls or
before artificial insemination in order to prevent contact between
BVD-PI calves and pregnant dams. Depending upon individual herd
management schemes the sampling could occur most conveniently during
calving or before turnout to summer or winter range.
- All aborted calves
- All purchased grafted calves
- All cows with BVD-PI positive calf
- All open cows not sold
- Cows not calved at time of sampling
- All cows that lose calf and calf not sampled
- Purchased open heifers
- Purchased pregnant heifers and cows (also test calf when born)
Sample to take?
Ear notch samples are optimal
- Easy to collect and ship(minimal equipment)
- Not affected by presence of maternal antibody
- Same sample can be tested by multiple test methods (PCR and
- Can be shipped “dry” in test tube or stored frozen
Submit “pig ear notcher” size ear notch (dime-size) in blood serum
tube (Red top tube) (One ear notch per tube). Label each tube
with individual animal identification number
What laboratory tests will be used for BVD-PI detection?
- Polymerase Chain Reaction (PCR): Not BVD-PI specific Used to
test pooled samples to reduce cost of testing
- Antigen-ELISA: BVD-PI “specific” is a one time test; Used to
test individual samples from a PCR positive pool in order to
identify individual BVD-PI animal.
Samples will be tested singly or pooled at WADDL depending upon
number of cattle tested (See Table below).
Pooled samples (up to 36) will be tested by PCR and individual samples
from positive pools tested by antigen-capture ELISA
What do the laboratory test results mean?
BVD PCR negative pool
No BVD-PI animals in pool
BVD PCR positive pool
BVD-PI or BVD-TI animal(s) present in pool requiring testing of
individual samples within positive pool by antigen-capture ELISA
BVD antigen capture ELISA positive individual
BVD-PI animal (98% accurate). If valuable breeding animal may
want to follow up with second sample in 2-3 weeks to confirm
BVD antigen capture ELISA negative individual
Not BVD-PI animal
How much will it cost?
* BVD Ag-ELISA testing on individual samples within
a PCR positive pool
BVD-PI (Persistent Infection) Ear
Notch Testing Program
Number of Cattle Tested
PCR Pool Size
PCR Charge per Head**
Ag-ELISA charge per Head**
up to 36
100 or more samples
up to 36
**Non-Washington state samples will be assessed a 50% surcharge.
What is BVDV?
Bovine Viral Diarrhea Virus (BVDV) is one of several world-wide
pestiviruses known to infect domestic and wild ruminants, camelids, and
swine. For cattle producers the virus causes economic losses through
decreased weight gains, decreased milk production, reproductive losses,
and death. There are many BVD virus types (cytopathic and
non-cytopathic). BVDV typing does not predict disease severity, and all
BVDV types are detected by current test methods. There are two
categories of BVDV infection.
- Transient (acute) infection (“TI”)
Short term (weeks)
Acquired after birth
TI cattle become immune and clear virus
>95% of BVD infections are TI
TI cattle minor source of virus spread in herd
- Persistent (chronic) infection (“PI”)
Life long infection
Acquired in utero. Thus, only fetal infection results in BVD-PI.
PI cattle never become immune
<5% of BVD infection are PI
PI cattle major source of virus spread in herd!
Over 90% of BVD-PI calves are born from normal dams (no prior BVDV
What is BVD clinical disease?
Most BVDV infection problems in cattle herds go unnoticed since 70-90%
of BVD infections are subclinical (do not result in observable disease).
When present, the most common disease caused by BVD virus infection in
cattle herds is poor reproductive performance including, abortions, poor
conception rates, stillbirths, and weak calves. In addition, BVD virus
infection causes suppression of the bovine immune system resulting in
increased susceptibility to other infectious diseases. In cow-calf herds
the immunosuppressive effect of BVD is normally noticed as increased
calf death loss (from scours and pneumonia) and poor weaning weight. In
feedlot animals this is noticed primarily as increased death loss and
incidence of respiratory disease (pneumonia). Lastly, BVD virus
infection alone can cause diarrhea with oral ulcers and bleeding
How is BVDV transmitted?
The main source of BVDV in cattle herds is BVD-PI animals. Virus in
BVD-PI animals is shed in all body secretions including nasal discharge,
saliva, tears, milk, feces, urine and semen. Transmission occurs via
ingestion, inhalation, and fomites (non-living sources such as boots and
vehicles). Some commons ways BVDV can enter cattle herds are:
Purchasing replacements at auction
Purchase of pregnant cow/heifer with PI calf
Introducing replacements or show stock without quarantine
Failure to maintain BVD vaccination program
Failure to test replacements for BVD PI
Contaminated semen or embryos
Borrowed or escaped bulls
Why test and remove BVD-PI animals from a cattle herd?
Persistently infected (PI) cattle are the major source of BVD infection
and disease in cattle because they shed huge amount of BVD virus
throughout their lives. The major economic loss associated with BVD in
cow-calf operations is loss of income due to loss of calves either
before birth (abortion), at birth (weak calves) or between birth and
weaning (BVD-induced immunosuppression make calves more susceptible to
common calf disease such as pneumonia and scours). Thus removal of
BVD-PI animals from a cattle herd should result in:
Improve reproductive performance in herd
Improve pre-weaning performance in herd (weaning weights and calves
Lower calf treatment costs and calf death loss
Provide more marketable cattle (BVD free certified herd status)
Can BVDV infection be eradicated from a herd with
No, BVD vaccination alone (with either modified-live or killed vaccines)
cannot keep a cattle herd free of BVD-PI cattle nor completely control
BVD infection according to the Academy of Veterinary Consultants and
American Association of Bovine Practitioners. Both groups promote a
three-pronged approach to BVD control, a combination of BVD-PI testing
and removal, vaccination and biosecurity.
Can I identify BVD-PI without laboratory testing?
Approximately 50% of BVD-PI calves are sick “poor-doers” that die before
1 year of age. However, the other 50% of BVD-PI cattle appear healthy as
calves, grow normally and enter breeding herds or feedlots unnoticed.
Despite looking healthy these subclinical BVD-PI animals still shed high
levels of BVD virus and require laboratory testing to identify.
How do I get BVD virus out of my cattle herd.
Current recommendations from the Academy of Veterinary Consultants and
American Association of Bovine Practitioners for control of BVD virus
infection in cattle herds focus on identification and removal of BVD-PI
animals. Control measures should include:
Diagnosis and removal of BVD-PI cattle
Vaccination to reduce BVD infection rate (Vaccination will not eliminate
BVD virus from cattle herds)
Biosecurity to prevent introduction of BVD-PI animals
What testing strategy should be used?
Testing for BVD-PI cattle is different than testing for many other
diseases because PI status stays the same throughout the animal’s life.
Thus, BVD-PI testing is usually done only once. A BVD-PI test may be
repeated to confirm a positive (since current laboratory testing by
antigen-ELISA or IHC has a small percentage of false positive results)
Meet with your veterinarian to determine your BVD goals and exposure
risk. Various testing strategies for whole herd testing exist. Below is
a common example.
- Prior to start of breeding season, test all calves and
non-pregnant females without calves. Isolate pregnant females until
they calve and test their calves.
- Prior to start of breeding season, test all bulls and
replacement heifers not previously tested for BVD-PI status.
- Maintain documentation of BVD-PI test results.
What do I do with a positive BVD-PI test result?
Quarantine animal until second confirmatory test is run (BVD-PI
“specific” laboratory tests, such at antigen-ELISA and IHC, have a low
(approximately 2%) false positive rate). A second ear notch sample taken
2-3 weeks after the initial test will ensure whether or not the BVDV
infection is persistent.
Ethically deal with confirmed BVD-PI animal by euthanizing animal,
selling animal to slaughter, or sending animals to feedlot that feeds
BVD-PI cattle. Don’t sell your problem to someone else.
Mother of BVD-PI calf should be tested for BVD-PI status. There is a
small chance (approximately 10%) that the cow is also BVD-PI. Cows with
BVD-PI calves that are not BVD-PI need not be culled. Remember, a
negative BVD-PI animal is negative BVD-PI for life.
How do I prevent BVD virus from re-entering my cattle herd?
The following management procedures could reduce re-introduction of BVD
virus into a typical cattle herd.
Maintain closed herd (not always practical)
Don’t purchase replacements from auction
Buy certified free or BVD PI tested livestock
Quarantine new arrivals and show stock for 30 days and test new arrivals
for BVD PI
Test purchased pregnant animal and its calf at birth
Keep records (reproduction and health)
Address health problems
Determine why cows abort, why calves are sick, and why animals die
Contacts at Washington State University for Consultation / Advice /
Interpretation of Test Results
|Dr. Tim Baszler
|Dr. Jim Evermann
|Dr. John Wenz
|Dr. Dale Moore
|Dr. Steve Parish