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Bovine Viral Diarrhea

Tuesday, June 25, 2019

NY) Bovine Viral Diarrhea PCR positive in a dairy calf.

Two dairy calves destined for the local county fair were tested for BVD at the AHDC. The veterinarian submitted EDTA whole blood and requested a BVD PCR on a pooled sample. The pool was positive and when tested individually, one of the two calves was positive. The veterinarian then sent in ear notches on both calves for BVD Antigen Capture ELISA (ACE) testing. Both calves were negative, which means they are not persistently infected (PI). The BVD PCR positive calf was acutely infected with BVD at the time of testing.

Fair season is just around the corner, and all cattle, llamas and alpacas going to the New York state or county fair need a negative Bovine Viral Diarrhea (BVD) PI test to ensure that persistently infected animals do not enter the premises. The New York State Ag and Markets regulations state “The testing veterinarian is responsible to make sure the proper test is conducted”. The BVD Antigen Capture ELISA (ACE) test is available for bovines only, and will determine if an animal is a PI or not. BVD ACE testing can be performed on an ear notch from cattle of any age, or on serum from a bovine 61 days old or older. The BVD PCR test is also available for cattle. It will detect both active infection and a PI; a positive result does not differentiate one from the other. Appropriate samples for BVD PCR include EDTA whole blood on cattle of any age, or serum or plasma from animals 61 days of age and older. If a cow is positive on a BVD PCR, a follow-up ACE test will be the next step to rule out a PI.

Camelid BVD screening is limited to the BVD PCR test, which is performed on EDTA whole blood on an animal of any age, or serum or plasma in llamas and alpacas 61 days of age and older.

BVD PCR testing is commonly used for cattle herd screening for BVD PI animals. Up to 10 cattle are pooled and tested at once. EDTA whole blood can be pooled from calves less than 61 days old, or serum, plasma or EDTA whole blood from cows over 61 days, can be pooled. Animals from the two age groups cannot be mixed, and sample types cannot be mixed. Please send individual samples to the lab. Samples are pooled upon arrival; we will not run pre-pooled samples. If the pool is positive, each sample will be run individually to identify the positive animal(s). At this time, there is no additional charge for the separate sample testing of a positive pool.

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