I had to google vasculitis when Dana said the vet told her that might be what's up with Cody.
Here's what I found. It's often an accompanying symptom to something else.
Did the vet draw blood?
I hesitate to post this because (1) it's Dana's horse and (2) this thread may not be seen :O)
But if anyone has anything to contribute please do. We will all be worried about that big gorgeous PMU foal - turned mature hunk of awesomeness.
GET WELL QUICK CODY!!