Pooled PCR Ear-Notch Screening Test for BVD

SDSU’s Animal Disease Research and Diagnostic Laboratory is now offering a new screening procedure for BVD, using ear notches from calves. Submitted ear notches will be processed much the same as for antigen-capture ELISA testing, then the fluid from each sample will be pooled for PCR testing.

Samples may be pooled in groups of up to 50 samples. Large submissions will be divided into groups of 50 plus a smaller pool, if a remainder exists. The cost for each pool is $60. The samples will be run once a week (individual antigen-capture ear-notch ELISA tests are run most days of the work week).

If a pool tests positive, individual samples may be tested with antigen capture ELISA to identify potential persistently infected individuals, at the regular cost of $4 per sample. This testing will not be done automatically but only upon request by the client; requests for individual testing should be made within 72 hours of notification of a positive pool.

Submission Guidelines. Fresh ear notches should be submitted in a manner similar to that for antigen-capture ELISA:

• Submit a fresh sample of ear tissue approximately 1 cm x 1 cm.
• Place ear notch in an empty plain red-top tube (no additive or gel).
• Samples not submitted as such are subject to an additional processing fee per tube.
• Tubes should be sent chilled on ice packs, observing proper shipment procedures.

Pooling samples in groups of 50 substantially reduces the per-animal diagnostic cost compared to currently available individual tests, yet maintains a reasonable number of samples to test individually in the event a pool is positive.

It is necessary to understand that pooled diagnostic procedures such as this should be considered screening tests only. In cases in which individual animals are represented as BVD PI-test negative (e.g. purebred animals for sale), individual diagnostics utilizing the ear notch antigen-capture ELISA, ear notch IHC, or serum ELISA should be performed.

Pooling procedures by their nature can result in decreased sensitivity over individual tests. Also, PCR procedures, due to their enhanced sensitivity, may detect transiently infected animals more often than other tests (such as the ear-notch antigen capture ELISA). Therefore, it is possible to experience scenarios in which a pool is PCR-positive but the individual samples are negative on the follow-up individual ear-notch tests.

SDSU’s ADRDL is committed to providing our practitioners with the latest and most useful tools for dealing with disease issues in their clients’ herds. The expertise and experience of our PCR personnel and our rigorous quality system allow us to make this test available now.

If you have any questions about the procedure, or proper submission of samples, please contact Dr. Jane Christopher-Hennings, Dr, Chris Chase, or Dr. Russ Daly at 605-688-5171.