Over recent years, new treatments have been developed and old ones rediscovered in the fight against abscesses.
Ultimately the best treatment is complete surgical excision, but often, due to the location or size of an abscess, this may not be possible. In these cases, one or a combination of the following treatments may be implemented.
Gels (e.g. Intrasite) help to stimulate normal tissue growth and repair at the edges and base of wounds. Some preparations also inhibit bacterial growth and some newer preparations actually contain antibiotics as a paste and can be used to pack the cavity and left for longer.
Antibiotic solutions can be soaked into gauze used to pack abscess cavities, but still need to be changed daily. This method – applying relatively high concentrations of antibiotic directly to the wound – allows the use of antibiotics which would be toxic if given systemically.
Care still has to be taken, though, because the drug may be absorbed into the body via the wound which can upset the normal gut function of the rabbit, which is dependent on friendly bugs which may be killed off by the antibiotics.
Dextrose – An ancient treatment coming back into fashion is very strong dextrose (sugar) solution. Normally, bacterial growth in the body increases as sugar concentrations rise, because bugs use sugar as a food source. This is why diabetic animals get more infections. However, a 50% dextrose solution is so concentrated that it not only inhibits the growth of most bacteria, but actually kills them by sucking the water out of them so that they die of dehydration. The dextrose can also help draw out fluid that would otherwise accumulate in the cavity. Dextrose solution is soaked onto gauze and packed into the wound, filling the cavity. The dressing must be changed at least once a day – otherwise fluid coming out of the wound will dilute the dextrose, and the dextrose may start to be absorbed into the body, negating its beneficial effects.
Manuka honey – In addition to being a strong sugar solution, as above, honey has antibacterial properties and has been used to treat infected wounds in humans for centuries. Honey promotes the formation of clean, healthy granulation tissue, and acidifies the wound, promoting healing.
Prior to commencing treatment with honey, the abscess will require surgical drainage and cleaning and removal of all the necrotic tissue and pus. Twice daily application (which owners can be shown to do), using a syringe to introduce the honey into the cavity is normally recommended. Treatment can be continued for weeks and it doesn’t matter if the rabbit licks at the honey.
Antibiotic beads: Some abscesses are too deep and painful to clean every day, or are inaccessible. Antibiotic-impregnated polymethylmethacrylate (PMMA) beads can be packed into the abscess cavity which is then sewn shut. The choice of antibiotics is not simple, as some do not work well with the beads and some may cause antibiotic-associated diarrhoea if ingested by the rabbit. The beads are left there for anything up to a few months and provide a slow but continuous release of antibiotic as well as filling in the hole left by the abscess and preventing it being filled by newly formed pus.
Calcium hydroxide has been used for many years treating facial abscesses in rabbits, with some success. The solution is syringed into the cleaned out abscess cavity and removed after a week or so. The main problem with calcium hydroxide is its effects on soft tissue. It is caustic, and causes tissue necrosis and nerves, blood vessels and muscles can be very seriously affected. For this reason many vets now steer clear of the treatment, but potentially it may still have its place in the treatment options of rabbit abscesses.
Hyaluronidase may help to break up pus and make it easier to remove.
N-acetylcysteine (Parvolex), also helps break up pus and mucus, as well as stimulating some immune functions and inhibiting certain aspects of bacterial activity. It can be very effective, but smells rather unpleasant!