The other question that still remained was why didn’t good immunity from vaccination protect these heifers from infection?
The investigation revealed another key point. During a very specific timeframe of employee changes on the dairy, this group of heifers likely did not receive its vaccinations. The puzzle now fit together nicely. A point exposure in a group of unvaccinated heifers during the critical time of gestation to create a PI calf. This was the perfect storm for such an occurrence.
So, what can we learn from this case?
1. Develop and follow SOP’s (standard operating procedures) that include your vaccination protocol. But remember, even in very well-managed herds such as in this example, protocol drift can occur. We must therefore rely on records and monitoring to catch this potential drift.
2. Herd biosecurity is important. Develop and follow herd biosecurity protocols. Also, ask these questions: Is my herd really closed? What are potential entry points for serious diseases such as BVD?
3. Continue to look for the zebra. Don’t get sidetracked from the important things. It is critical to maintain surveillance for the unlikely. If we do not look for it, we won’t find it. Diseases like BVD are, unfortunately, still alive and well in the cattle population.
Mark J. Thomas is a veterinarian and partner in Countryside Veterinary Clinic, LLP and Dairy Health & Management LLC in Lowville, N.Y.