2-year-old PEW not oxygenating well?

Question
We saved our PEW from the middle of our street -- we think it was escaped
(or liberated) snake dinner. She's two years old and recently (five months ago)
recovered from a respiratory infection that had her quite blue. We just got a
dog (a very docile greyhound) and things have changed in the house. Lately
she's lethargic, and today we noticed that her feet, ears, and nose seem less
rosy, very ashy pale. She's also breathing harder; not rasping or sneezing; we
know how to look for that. Could it be that she's close to the end of her life,
or that stress from the new animal in our lives is making her age
prematurely?

Answer
the sounds of it, she either has an advanced myco flare or she may be suffering from heart disease, congestive heart failure, which causes a lack of oxygen and will cause the color change in her extremities. I doubt the dog has anything to do with it unless he's tormenting her relentlessly while you're not around. At two, she's an old lady, but her life isn't over. I do encourage you to research her condition more, preferably with a vet who knows rats, and see what you can do to help her out.