When the abscess was opene, it was found to be full of thick green pus, which went much further into the rat's face than was originally thought, leaving a deep cavity that now has to be kept exceptionally clean and open, and antibiotic powder is put into it as well as oral antibiotics being given.

Here is Rosie after surgery.

It's very important to keep abscesses open and clean so that they are able to heal from the inside, out.