Hi there, sorry you are dealing with this, abscesses are so stressful. I had a bun with a jaw abscess a few years ago.

The best course of action is to treat it aggressively, so that usually means surgically cleaning out the abscess and giving antibiotic injections (usually penicillin) for several weeks.  Rabbit abscesses are full of a very thick pus and have a very thick capsule, so they don’t drain the way other animals’ do. Sometimes when a bun is very weak, the vet might prescribe just the antibiotic shots, but this isn’t usually enough to cure the abscess, it just prevents it from growing. But long term this can be hard on the bun as well. My bun’s abscess cleared up after the first round of surgery and antibiotic injections, but sometime repeated procedures are needed to really get rid of it. I found giving the antibiotic shots at home to be relatively easy once I did it a few times (easier than syringe feeding IMO).

If he is in good health otherwise, I don’t think 7 is too old to treat this the way the vet proposes. You might get a second opinion if the vet is not very confident. Blood work prior to anesthesia could be informative.

Has he had an x-ray of his teeth or any other imaging? Sounds like this all could be dental in origin. Before launching into surgery, it would be good to know the extent of what you are dealing with and if there is a root cause. If available in your area, a CT scan could give you a lot of information (such as if there are other abscesses that you don’t know about) and help you know how successful treatment is likely to be.