Visit with a Vet: BVD Testing at the Georgia Veterinary Diagnostic Laboratories

Originally published in the Sept. 18, 2013, issue

Visit with a Georgia veterinarian in this monthly feature. This edition comes from Drs. Lee Jones, Roberto Palomares, Sree Rajeev, Susan Sanchez, Murray Hines and Jeremiah Saliki of the diagnostic laboratories in Athens and Tifton. 

BVD – one complex disease, one simple sample, one simple strategy!

Bovine viral diarrhea is a significant cause of economic losses to the cattle industry. Clinical signs include reproductive failure, respiratory disease or diarrhea. About 70 percent of infected cattle don’t become sick, but are susceptible to other diseases. Moreover, some animals showing no symptoms are dangerous to the herd as they can be virus carriers, also known as persistently infected animals, or PIs.

PIs are calves infected with certain non-cytopathic strains of BVD in the womb. Although many infected calves die or are culled within six months, some grow into adults. These shed large amounts of the virus in secretions such as saliva, feces, urine and milk throughout their lives, exposing the herd to BVD.

PIs can transmit BVD by direct contact, such as nose-to-nose, or through contaminated veterinary equipment, farm equipment or facilities. To manage BVD, vaccinate all dairy calves at 2 to 3 months old and all beef calves at 4 to 5 months. Add biosecurity procedures to prevent introduction of the disease – isolate and confirm that new animals are BVD-negative; bio-containment to interrupt virus spread; and laboratory testing of samples for BVD presence.

To diagnose a disease such as BVD in an animal or herd, laboratory testing is required. The same is true for whole-herd screening as part of a herd health program.

Diagnosis

When an animal is sick, it is recommended to take eight milliliters of whole blood in EDTA, a combination of a specific acid and a colorless, water-soluble solid typically placed in a purple-topped tube for veterinary purposes. In the case of abortion or death, it is recommended to take samples of lung, spleen, lymph nodes, kidney or the entire fetus.

Herd screening or animal marketing:

To test the herd for PI screening, or to market an animal after confirming it is not BVD-PI, it is recommended to take one ear-notch sample in a screw-capped tube or blood in a red-topped tube. When BVD-free bred heifers are purchased, it is still necessary to test the calf after birth to ensure BVD won’t be accidentally introduced. Diagnostic labs can pool up to 24 ear-notch or blood samples and run one test, called a PCR, to reduce costs per animal, with a turnaround time of two to three business days. If any pool is positive, all members of that pool will be re-tested for BVD using the Antigen Capture ELISA test. This individual animal testing may present an additional cost and turnaround time, but will identify and allow removal of PIs.

Table 1: Testing strategy for PIs. Tests, price and turnaround time of laboratory testing

# of samples received at once	PCR pool size	PCR cost per head	Time to results (PCR)	ACE cost per head	Time to results (ACE)
1-5	NA	NA	NA	$5.00 plus $10 Setup fee	24 hours
5-23	NA	NA	NA	$4.50	24 hours
24 or more	24	$2.5*	2-3 business days	$3.50	24 hours

 

To contact the diagnostic labs, call 706-542-5568 for Athens, 229-386-3340 for Tifton.