They had the vet out twice a couple weeks ago when they started losing calves. They lost 8 calves as of last Friday. I tried to catch up with them when the vet was out the last time to do culure/blood work on them ( I think is how they determined it) but couldn't find which circle they were on.
The calves were flat out sick. Droopy ears, hard breathing, etc.. They moved the pairs about 3 miles to a new circle on a pretty warm day, but that night it got really cold. Then a few days later a couple calves were dead. The vet thought the move may have brought it to the front of the issue. They were going to wean the calves a couple days later, but when this started, they have left the calves on.
This is all second hand from my buddy on what all has happened, so don't quote me. I did see the cattle one day and they looked pretty bad. They have to use the gun so they don't get the cattle to worked up.
We haven't had any problems with ours this year and we didn't pre-vaccinate before we weaned, just did it the day we pulled the calves. I think next year I might use a vaccine just incase.