If you've ever been around ehd, you'll know that unless you are in the pen with them at least every couple hours they can be fine in the morning and dead by noon, it happens that fast more times then over a couple days. The ones that I noticed looking sick lived through it and the others were just dead within hours and I'm in my pens every couple hours daily. Usually when they look sick it's too late. I just recieved my vaccine from the deer breeders corp, $14 per deer for the 2 shots, one and then a booster 2-4 weeks later. Good luck either way, it's bad stuff for sure. Last year our whole state lost thousands in the wild and they say up on the Milk River in Montana they lost as many as 90% or more in places.