It is not uncommon for rabbits to suffer abscesses in various locations of the head, including the jaws (maxillary or mandibular), and behind the eyes. In many cases, these infections are associated with molar problems. Because rabbits engage in cecotrophy (ingestion of cecotropes, the abscesses commonly contain bacteria found in the mouth and intestine. This can make treatment problematic, as the antibiotics used to treat the infection must not also kill beneficial intestinal bacteria, which can cause life-threatening cecal dysbiosis.

Until only a few years ago, the only option for treatment of an abscess of the head in a companion rabbit was invasive surgery, debridement of the site, and implantation of antibiotic-impregnated beads to effect slow release of bacteriostatic or bacteriocidal compounds. More recently, medical treatment with specific antibiotics has been shown to eliminate the need for such invasive practices.

An excellent study on Periodontal Bacteria in Rabbit Mandibular and Maxillary Abscesses not only identifies the bacteria most commonly responsible for jaw abscesses/osteomyelitis in rabbits, but also provides information on the antibiotics most often effective against them. The investigators found that 96% of the bacteria found in rabbit jaw abscesses were sensitive to penicillin, and that 100% were sensitive to clindamycin.

Because lincosamines (e.g., clindamycin) and penicillins cause fatal cecal dysbiosis and enterotoxemia in rabbits, they cannot be orally administered to treat head abscesses. Clindamycin, while effective, is dangerous even when injected, as it does travel to the intestinal tissues and can cause problems there. When used in slow-release resin beads implanted in an abscess site, they clindamycin can be effective. However, because of the risk of the clindamycin entering the mouth and intestine via a jaw abscess, some vets prefer not to use this potentially dangerous drug for rabbits.

Injectible Penicillin G Procaine is considered the only "safe" penicillin for rabbits. When combined with Benzathine (a combination known as "bicillin"), the drug remains longer in the body, which may allow it to better penetrate the thick, caseous pus of the rabbit abscess. Bicillin injections every other day for several weeks have effected excellent cures in rabbit abscesses that might have been considered untreatable only a few years ago.

A very early article, "Successful Eradication of Severe Abscesses in Rabbits with Long- Term Administration of Penicillin G Benzathine/Penicillin G Procaine" by  Marcy E. Rosenfield (Moore) describes several successes with bicillin treatment. These have since been repeated in hundreds of companion rabbits suffering from severe jaw abscesses, usually with excellent results. Although this report is more anecdotal than scientific, it offers useful protocols for bicillin therapy, as well as successful case studies.
  The bicillin treatment is now considered by many rabbit-experienced veterinarians to be the "first choice" protocol for retrobulbar, inner ear (often accompanied by torticollis or "HEAD TILT"), and molar root infections in rabbits.

If your vet is unfamiliar with this protocol, you might wish to print the article linked here and bring it with you when you go for your bunny's examination.