Protecting your herd from this hidden virus
Bovine Viral Diarrhea, or BVD, is one of the most persistent threats to herd health. Infected cattle carry the virus for life, spreading it and reducing overall herd performance.
Veterinarian Dr. Ethan Hill explained that PI cattle become infected with the BVD virus while still in the womb, typically between 30 and 120 days of gestation.
“Their immune system is so naive that they don’t mount an immune response, so they just become persistently infected,” Hill said.
Once born, PI calves act as constant sources of infection within a herd. Their presence can quietly compromise herd health, leading to slower weight gain, reduced feed efficiency, and rising veterinary costs over time.
Hill said PI calves are often “poor doers,” meaning they struggle to thrive.
“They’re always sick, showing signs like coughing or nasal discharge, they don’t produce very well, and they tend to stay smaller, kind of like the runt of the litter,” Hill said.
He noted that infected cattle can cause reproductive losses, including abortions and lower conception rates, while the constant shedding of the virus increases stress across the herd.
The disease can also spread to other operations when infected animals are sold or come into contact with new cattle.
Managing BVD-PI begins with strong biosecurity and testing protocols. Hill emphasized that prevention is far less costly than dealing with an outbreak.
“Any time you buy new livestock or replacement heifers, you should quarantine those animals for two to four weeks before exposing them to your herd,” Hill said. “Testing new additions is equally important.”
One of the most practical and cost-effective testing methods is ear notching, which involves sending a small tissue sample from the ear to a diagnostic lab.
“If you see a calf that’s showing signs of BVD, like stunted growth, respiratory problems, or poor performance, you can do an ear notch on that one,” Hill said.
Vaccination is another vital tool for controlling BVD. Hill encouraged producers to make it a part of a consistent herd health program, paired with quarantining new animals, maintaining strong biosecurity and testing any calves showing signs of infection. Animals that test positive should be culled immediately to prevent the virus from spreading.
While BVD-PI may seem like a distant threat, Hill reminds producers to remain proactive.
“Due diligence is important,” Hill said. “If you suspect PI cattle in your herd, contact your veterinarian and get them screened or tested.”
With careful management, routine vaccination and an effective biosecurity plan, producers can protect their herds from BVD-PI and avoid the long-term losses this hidden virus can cause.
