In recent articles, bovine viral diarrhea virus (BVDV or just BVD) has been discussed and how this virus is present and affecting large numbers of dairies.

A large range of clinical signs is associated with BVD infection due to its immune suppressive nature. This allows for other common diseases like scours or respiratory disease to become a bigger problem. Let’s look at the calves as to things to look for and what you might do if you see them.

The calf
If you are the one that is out in the pen with the fresh cows, are the calves born normal size with decent vigor at birth? Are there too many stillborns? If you are raising calves, do you have an abnormal or increased incidence of scours or respiratory disease? These are very general overviews, but in dairies that we have seen problems, these have been some of the initial signs that BVD was an underlying contributor.

The first step is to bring it to the attention of the herdsman so that he can have a discussion with the owner and herd veterinarian. Monitoring calf health is critical in any disease and having good treatment and diagnosis data helps the dairy improve. Do not accept the fact that too many calves die or are slow at birth even after you have provided them four quarts of good quality colostrum within four hours of birth. If you are handling and caring for calves appropriately and providing the proper nutrition, death-loss and sickness should be minimal on the dairy.

If BVD is part of the problem, we have found that PIs (persistently infected) calves are the main source of the infection. It is easy to identify the PI, if present, by a diagnostic test. A small ear notch sample can be taken from each calf at birth and frozen to send in for diagnosis. When the animal is tagged, the number of the calf is written on the sample tube. If the calf is found to be negative, this also means that the dam is negative. By testing all calves, we also protect the milking herd from allowing an adult PI into the herd. If a commitment cannot be reached to test all calves born, operations that are experiencing high sickness and death-loss on calves can test the dead ones. If a PI is found, it would then be best to start sampling all calves born because about two-thirds of PL calves look normal and do not die in the first 6 months.

BVD control also involves proper vaccination. Make sure you follow directions as to how you handle and give each calf the shot. Building up the calf’s immune system is critical for BVD but also for other viral and bacterial diseases that can affect the animal’s health and production.

Next time we will discuss signs to look for in adult cows and how sampling milk is an easy way to identify if BVD is causing problems in the milking herd. EL

Bruce W. Hoffman
DVM
Animal Profiling International, Inc.

This article topic also appears in Progressive Dairyman. This article has been written specifically for dairy employees. The article in Progressive Dairyman is written for dairy owners and herdsmen.

El Lechero recommends dairy teams read the articles and then discuss how to apply these principles on their own dairies.