hematuria

Question
There's an illness going on in my home. I've lost 5 rats so far.
It all started with April at my mom's place. She had hematuria but very mild. We figured bladder infection so put her on baytril. She cleared up fast. Two days later a boy in a different cage had severe bleeding. We could not confirm that it was hematuria. A few days later in same cage as the boy, there is another bleed and this time definitely hematuria. He recovers. Meanwhile, in my home, (we live in the same triplex) I had a girl with hematuria. She recovers. A week after all this... my Boo same cage as the girl becomes sick and dies. Postmortem shows a trauma to the urethra. Two weeks later, I lose 3 more rats to this illness. The other two postmortem comes back with the same thing to the urethra. We are doing a toxicoly and another histopathology. But everyone is at a loss as to what this is and how to stop it.
My rats are on Harlan Teklad and Oxbow blocks and daily fresh veggies. I believe they are testing the blocks as well. My vet is working with the University of Guelph but I was hoping that others might have answers more quickly.
Thanks

Answer
 Wow, that is very strange.  I'm afraid I'm at a loss as well =(  Usually blood in the urine is because of a bladder infection, kidney infection, kidney stone, or organ failure.  It certainly does sound like a virus; it would be a huge coincidence to have so many rats die of anything else.  There's three major illnesses of pet rats, SDA, Sendai Virus, and KRV.  Here's the Rat Guide's info on those three if you haven't already read them:
http://ratguide.com/health/viruses/sda.php
http://ratguide.com/health/viruses/sendai_virus_sv.php
http://ratguide.com/health/viruses/kilham_rat_virus.php

 None of those list bloody urine, but I know when a rat's organs are failing blood in the urine is often seen.  The lab results should show something, hopefully.  Let me know what happens; I'm really sorry I couldn't tell you anything more, but I certainly hope everything turns out well for you and your ratties!