I too have a glider with an abscess. On Jan. 19th before heading to bed I always check in on all my animals. I thought I noticed that one of my gliders had a tiny bump on the side of his face. I could not get a good look since he is untamed and would not sit still. After a while I gave up and decided to head to bed and I would look at him first thing in the morning. The next morning when I got up I  checked on him right away. I discovered to my surprise the left side of his face had swelled up. The lump was the size of half of his head! I called the vet right away to see if I could get him in that morning. I was able to get an appointment right away. At the vet the poor little guy was so scared that he first took a chunk out of the vet's hand then one out of mine. The vet could tell just by looking at him that it was some sort of abscess but could not be sure what caused it with out a complete exam. The vet then decided to sedate him to examine him and to do any procedures all at once. They drained the abscess and put him on Baytril. By the evening I was surprised after everything he had gone through, he was up and eating and running around.
Jan 23. The little guy has improved by leaps and bounds. He is still active and eating well.
Just thought I would share this with you.