Bovine viral diarrhea virus persistent infection (BVD-PI) Ear Notch Testing Program for Cattle Herds

Cows in field

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 programs.

The Washington Animal Disease Diagnostic Laboratory (WADDL) at Washington State University has implemented the 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.

What is Bovine viral diarrhea virus?

BVDV is one of several worldwide 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 can be detected by current test methods.

There are two categories of BVDV infection:

  • Transient (acute) infection (TI): Accounts for more than 95% of BVD infections. Infection is short-term (weeks) and acquired after birth. TI cattle become immune and clear the virus. TI cattle are a minor source of virus spread in herds.
  • Persistent (chronic) infection (PI): Accounts for less than 5% of BVD infections. Infection is life-long and acquired in utero. Thus, only fetal infection results in BVD-PI. PI cattle never become immune and are a major source of virus spread in herds. More than 90% of BVD-PI calves are born from normal dams (no prior BVDV exposure).

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 like pneumonia. Lastly, BVD virus infection alone can cause diarrhea with oral ulcers and bleeding disorders.

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). 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 weaned)
  • Lower calf treatment costs and calf death loss
  • Provide more marketable cattle (BVD-free certified herd status)

Can I identify BVD-PI without laboratory testing?

Approximately 50% of BVD-PI calves are sick “poor-doers” that die before a 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.

What animals should be sampled for BVD-PI?

  • Calves: All calves, whether they were aborted or born alive should be tested. Testing and removal of BVD-PI calves must occur before exposure of females in the breeding herd to bulls or before artificial insemination 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. Purchased grafted calves should be tested as well.
  • Cows: All cows with a BVD-PI positive calf, open cows not sold, cows not calved at time of sampling, and cows that lost a calf that was not sampled should be sampled.
  • New entries: Purchased open heifers, purchased pregnant heifers and cows (also test calf when born), and bulls should be tested.

What samples are needed to test for BVD-PI?

Ear notch samples are optimal for several reasons:

  • Easy to collect and ship
  • Not affected by presence of maternal antibody
  • Same sample can be tested by multiple test methods (PCR and antigen-capture ELISA)

Ear notch samples can be shipped “dry” in test tube or stored frozen. Submit “pig ear notcher” size ear notches (dime-size) in blood serum tubes (red top tube, one ear notch per tube). Label each tube with individual animal identification numbers.

What laboratory tests are 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 the number of cattle tested. Pooled samples (up to 36) are tested by PCR and individual samples from positive pools are 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

What do I do with a positive BVD-PI test result?

Quarantine the animal until a second confirmatory test is run (BVD-PI “specific” laboratory tests, such as antigen-ELISA and IHC, have an approximately 2% false positive rate). A second ear notch sample taken 2-3 weeks after the initial test will ensure results. 

Ethically deal with confirmed BVD-PI animals by euthanizing, selling to slaughter, or sending to a feedlot that feeds BVD-PI cattle. Don’t sell your problem to someone else.

Mothers of BVD-PI calves should be tested for BVD-PI status. There is a small chance (approximately 10%) the cow is also BVD-PI. Cows with BVD-PI calves that are not BVD-PI do not need to be culled. Remember, a negative BVD-PI animal is negative BVD-PI for life.

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 include:

  • 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

What testing strategy should be used?

Testing for BVD-PI cattle is different from 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 the 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.

Can BVDV infection be eradicated from a herd with vaccination?

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 that includes a combination of BVD-PI testing and removal, vaccination, and biosecurity. 

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

How do I prevent BVD virus from re-entering my cattle herd?

The following management procedures could reduce the 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

How can I get more information about BVD testing?

Contact Dr. Claire Burbick by email at or by calling 509-335-9696. Dr. John Wenz at the WSU Veterinary Teaching Hospital can also be contacted at or 509-335-0773.

Page revised June 2019

Categories: Cattle