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!!