My rat has a wound...

Question
I have a Blue Rex Rat (Adolf). And a Fancy rat (Kalipso).  Kalipso is 6 months
old, i raised him, and Adolf is of questionable age, i bought him form the pet
store and of course they didnt know. Well. After introducing the two. I felt
they were well enough together after a couple 15 minute meetings spread threw-out the week. Well, i took Adolf out the other day and noticed he had
battle wounds.  A few scratches. But now one of the scratches on his back
had scabbed over. And he was healing very nicly, they were getting along
great, cuddling and even drinking water at the same time. Perfect little
brothers. ANYWAYS. Today i took them out to play, and after a while i picked
Adolf up, and the scab on his bacj had poped, and had like.. wierd fluffy/
oozy green pus like substance sticking out of it. So i rubbed it off, and the
wound is open, with the greenish looking stuff inside. WHAT is it? Is it
infected? How do i clean it? Does he need to see the vet? Im worried about
him because he has respiratory problems as it is..He's a little wheezer.

Answer
 It sounds like an abscess, which probably resulted from a wound that got infected.  It would be a good idea to see a vet, as infected wounds usually require a course of antibiotics to heal properly and quickly.  The wound will also need to be flushed out with sterile saline and the outside swabbed with an antibacterial surgical scrub.  The vet will also shave the area to make it easier to clean.  If he is having respiratory problems it would be a good idea to go to the vet anyway, and the same antibiotics for his wound will likely clear that up as well.

 If you can't afford to take him to the vet, clean the wound as best as you can and put some antibacterial ointment on it.  You can also use warm compresses to draw out the pus.  If it doesn't get better within a few days, or gets any worse, you'll have to take him to the vet right away.

 Good luck!