I have an extremely sick little love named Pancake who is unfortunately suffering from seemingly untreatable Mycoplasma (she's been through several rounds of Baytril and Azithromycin) and what appears to be potential kidney failure. She's still a little cuddlebug and doesn't show much indication that she's ready to be out of this mess, so I do the best I can to keep her comfortable and happy while she's still content being my (and her sister, Jackie's) close companion.
I just wanted to share an article my wonderful vet gave me when Pancake was first diagnosed. I'm sure many of you have seen it, but for those who haven't, it is, without question, the most informative and fantastic article I've read about rat respiratory diseases, specifically Mycoplasma.

Rat Respiratory Disease: What Causes It, and What You Can Do About It
Authored by: R.S. Hines DVM, PhD
http://www.veterinarypartner.com/Content.plx?P=A&S=0&C=0&A=1437

I really hope this helps anyone seeking advice on this painfully common ratty ailment...a bad flareup of Mycoplasma absolutely heartbreaking to witness. Pancake's began after having 2 massive tumors removed--one of the many post-surgical complications she's endured these past few months. My little spitfire, Jackie (also Pancake's sister), also had mass removal surgery the same day as Pancake, and while there were quite a few physical complications (forcibly pulled-out surgical staples, for example), she's doing just fine in the respiratory department. It just seems like Pancake's immune system really couldn't take the surgery and the many complications that followed, and reacted with a severe flareup.