11 month old house bunny

Question
Around Thanksgiving of last year (2012), my bunny (9 months old then) was attacked by my wiener dog in the face. Her mandilla was almost fractured and the vet had to wire her mouth for 6 wks. She also had a fractured lower incisor which became infected and was surgically removed two weeks ago. The vet said because of the pus he was not able to get a few fragments, but thinks he got enough "root to bone". We had her pus cultured and it came back yesterday as anaerobic and the vet has her on two oral medicines - Metronidazle Susp 100mg/ml;  SMZ-TMP 48mg/ml per 30ml-A&E, twice a day for 30 days. My question is are the "tooth fragments" he left behind going to keep causing infection and does she have a good chance of kicking this infection completely?  She still has a mass under her chin which the vet said will probably have to be drained one more time, but the infection should be gone.  We've spent thousands of dollars trying to save this bun's life and if the infection comes back AGAIN, do we keep trying.  The vet said there is one more antibiotic that we can try, but toxic to humans and we cannot get on our skin, but okay for rabit to ingest.  He said that we can always go back in and try to get tooth fragments, but I am not sure I want to put her through that again.  When do we say enough, she has been through sooooo very much and this is not about the money, but for her.  We love dearly and want to save her, but don't want her to keep suffering.  Thanks for your help!

Answer
Dear Kate,

If you have not yet tried dual-acting Penicillin-G Procaine/Benzathine, then I would give that a shot.  If there is still infection in the jaw, then the bones will not heal properly.  Even if they heal, they will probably no be straight, and your bun will have a lifelong problem with malocclusion (this can be dealt with, but it will be chronic).

In my experience, SMZ-TMP is pretty much useless against the organisms in a typical jaw abscess.  Please see:

http://www.bio.miami.edu/hare/jawabscess.html

As far as "how much is too much"?  Only you can decide that.  I am not there to see her condition, her outlook on life, her will to live.  Provide her with plenty of pain management:  metacam plus tramadol can be very good for bone pain.

I suspect the vet wants to try chloramphenicol.  It might work, and it might not.  And the other thing to consider is that a culture from a jaw abscess might not give very accurate results, since there's a very good chance to get contaminants from the mouth.  I would not be surprised if there were multiple, opportunistic pathogens in there.  

If this were my bun, I would seriously consider the dual-acting penicillin.  We have seen practically miraculous results with this, if the bacteria are sensitive to penicillins.  And if the culture indicates they are not, then consider the possibility of misidentification of the real pathogens.  At this point, if it's life or death for the bunny, it certainly can't hurt to try the dual-acting Pen.

Our vets use 50,000IU/kg once every 48 hours, subcutaneous injection only.  Draw back on the plunger once the needle is under the skin, to be sure you have not hit a blood vessel (which can be disastrous).

I hope this helps.

Dana