Bovine Viral Diarrhea

[Oxankle]

This winter one of my cows seemed always dirty. I watched her, she never lost weight or condition but constantly had diarrhea. The whole herd is vaccinated for BVD, but when I took some heifers in for their bangs shots I took her along and asked the vet to test for persistent BVD and Johnnes.

Test came back positive for BVD. Vet told me that it would show up as unthrifty calves, abortion, respiratory problems. "Cull her and any of her heifer calves".

She is a young cow, her first calf never thrived and I clamped it, sold it for beef. Her second calf looked good but died during the recent ice storm of what I thought was pneumonia--and it probably was.

Anyone else ever encounter this? The Jeffers vet supply catalogue says that BVD will occasionally break through a vaccine but this is the first time I've seen it. Sure ruined a nice looking cow.
Ox

She is Persistantly Infected. We have dealt with it. Basically, what happens is that she was infected as a fetus. There is a window where the fetus can be infected and it will recognize the virus as part of the body system. A PI cow will always have a PI calf, and if another cow in the herd picks the virus up at the wrong time she can also have a PI calf. At the wrong time she will likely abort. If you don't vaccinate you will likely see unthrifty calves, calves with persistant diarreah or abortions. Even if you do vaccinate you may see some of the above symptoms. Whatever you do you should get rid of her. My suggestion would be to put her down, or at the very least make sure she is sold for slaughter only.

The case we dealt with was in a 2 1/2 year old heifer, when we discovered the problem we put her down. We saw many of the above symptoms, but never had many abortions. We also started vaccinating the next spring, and the # of "scrub" or unthrifty calves we had has almost vanished. Also our abortion rate has gone from 2-4 a year to 1-2.

[Oxankle]

Randiliana:
What you said about the effects of a persistent infection is just what the vet told us. The cow will go to slaughter. Our herd is all vaccinated, but apparently the infection broke thru on this cow. You can bet we will be watching closely to see that all the vaccinations are on schedule. One calf saved will pay to several years vaccine costs in a small herd.

What irks me is that this cow is one of our best; always in condition, lots of milk, thrifty. She is just lost and will bring only salvage price.

It sure makes me look for ways to go to modified live virus vaccine.
Ox

It happens. No vaccine is 100% effective. If an animal is under stress or sick at the time of vaccination, then the vaccine will be less effective. Which could have been what happened with this cows dam. OR this cows mother may have been PI without you knowing it. We were at a meeting that discussed BVD, and they told us about a dairy herd that consisted entirely of PI cows. It is one of the more productive herds in Canada amazingly. But, what they said was that some cows can go on to have long (I belive he said one cow was 12 years old) and productive lives where no-one would have known their PI status if they hadn't been tested. Vaccinating will not cure a PI animal, and a PI cow will ALWAYS have a PI calf.

[willow_girl]

Ox,

Sorry about the loss of a nice cow.

The DHIA I worked for until just recently offered an economical, milk-based BVD test ... something you might want to look into if you're thinking of having the whole herd tested.