If you are not a cattle producer, when I use the term BVD you may think I am referring to underwear. If you are a cattle producer, you may know what I am talking about when using the term BVD. If you are a cattle producer who vaccinates against BVD, you are certainly aware of the virus. If you are a cattle producer who has had to deal with the results of BVD in your herd, you may be trying to figure out how much your underwear will bring in a yard sale because you have certainly lost money.
Bovine viral diarrhea is a potentially devastating virus that can affect cattle in a number of different ways with none of them being good. All of the signs of the virus are somewhat non-specific such as poor production, lameness, ulcers in the mouth or other areas with mucous membranes, diarrhea and abortions. The virus may exist in a herd without causing a lot of obvious damage, yet the virus may be like an iceberg. It is what is below the surface or what is not readily seen that is the problem. When the virus hits a herd with a vengeance, it is like a ship running into the iceberg.
In discussions with the folks at our diagnostic laboratories, I am reminded of how expensive it can be to have the BVD virus get into a herd of cattle. One incident related to me was of a producer who lost five calves that were two- to three-week-old when they died. When the producer lost the fifth calf, he took it to the lab, where BVD was diagnosed. As I mentioned above, abortions and early embryonic deaths can result from BVD. What may be even worse are the infections that may occur in the womb or even shortly after calves are born. Somehow those losses seem worse — those occurring after a calf is born and then it crashes. It is a little like the taxes they take out of your check. I may look at my check and not be very happy, but if my accountant tells me to write the IRS a check after it has made it to my bank account, that seems to hurt worse. Either way, you can do the math. To lose five calves to the BVD virus is like taking a sucker punch to the stomach.
Another incident involved a farmer who was feeding bottle calves. Out of 25 calves, he lost five. The culprit was BVD. I haven’t talked to anybody lately about the profit margin for raising bottle calves even if everything goes fine, but I suspect if you can make 20 percent on your money that’s fairly good. The best I can tell is, if you lose five out of 25, that seriously gets into the profit margin. And although I haven’t ever raised bottle calves, I do know it is extremely labor intensive. Fortunately, farmers do not count their time as an expense or that kind of loss could be devastating.
Another story related to me was of a stocker grower who was having a high incidence of respiratory problems and had lost a few calves to pneumonia. After submitting samples to the Auburn laboratory from a calf that died from pneumonia, it was determined BVD was involved. It is likely one of the calves he had lost was what is known as a persistently infected animal.
Calves become persistently infected when they are exposed to the virus while in the mother’s womb prior to 120 days of gestation. I like to think of it like the Trojan horse. You probably remember the story where Greek soldiers (probably the equivalent to our Navy Seals) got into a great big wooden horse somebody from the city of Troy had ordered. Then when the Trojans brought the horse into the city, the Greek special forces guys got out at night and defeated the Trojans (or something like that). Anyway, what happens with these persistently infected calves is that the virus gets in there before the immune system is at a stage of development that it recognizes the BVD virus as being foreign. So the virus sets up housekeeping and pretty much multiplies unimpeded. While most of these PI calves die very early, others do not. Those that live shed huge amounts of the virus and basically wreak havoc. It is often the case that a PI calf sheds so much virus even those others vaccinated against BVD eventually have their immune system overwhelmed and they become ill also. If you play the odds, you are not going to buy a PI calf. However, if you find yourself with a PI calf, you could have been better off investing with Bernie Madoff.
Fortunately, there are a few practices that stack the deck in your favor when buying calves. First, no matter what disease you are trying to prevent, you need to have a way to quarantine new additions into your herd. If you buy from a reputable producer who can provide you with a history of the herd of origin and vaccination history, quarantine may not be a top priority. If you are purchasing calves who cannot trace their ancestry beyond the sale barn, I recommend you keep these separate from your herd for at least two weeks. In addition, you may want to have new additions tested for BVD to make sure you are not introducing that virus into your herd. Discuss biosecurity measures such as quarantine and testing with your veterinarian. I figure it is sometimes like the old advertisement for FRAM oil filters. You can pay now or pay later. I recommend the now option. It is usually less expensive.
Finally, my interest in BVD is that it may look like some regulatory diseases like foot-and-mouth disease and vesicular stomatitis. I try to never miss an opportunity to ask producers to call me or their local veterinarian when you see ulcers in the mouth of a cow or even a horse. It is extremely likely it will not be a foreign animal disease. However, we do not want to miss or dismiss the importance of making sure these cases are not a foreign animal disease. And while we are at it, we may be able to help you and your veterinarian develop a plan to show BVD the exit sign if that is what the problem turns out to be.
Dr. Tony Frazier is the State Veterinarian for Alabama.