Wednesday I found one of my biggest bull calves (500lbs) dead. Bleeding out the eyes nose and rectum. I did a count and found I was missing another big bull calf. Found him up the valley dead by about 2 days. All the other cattle seemed fine.
Friday night, I noticed another big bull calf and two small heifers acting a little mopey. I called the vet today and she gave them IV fluids and mineral oil to flush them out. All three died anyway with the same bleeding as the first two.
No fever, just got weak really fast and started bleeding out of rectum and eyes right before death.
Vet cut one open and didn't find anything wrong, but says it is renal failure (kidneys). Found a cyst on one kidney they looked inflamed.
Vet says she's pretty sure it was something toxic that they were eating, but didn't find any acorns or oak leaves in the rumen. She is going to send tissue samples in for tests, but says don't be too surprised if they're inconclusive.
As soon as I found the first one dead, I opened up some new pasture for them to keep them away from the woods. Today, I locked them all in the cow yard with hay to be sure. It sounds like there's nothing else to do but wait.
Has anyone ever had something similar happen? It sounds like it could still be acorns poisoning even though there weren't any in the rumen. But maybe it's some other plant? (I'm in SE MN) There are plenty of oaks in the pasture, but it's a big pasture and I've never had a problem before. Pasture was getting short, but there was still plenty to eat. Also these calves were still nursing so I can't imagine they were exactly starving.