Hope this suggestion works for you as well as it does for us.
We use GSE oil (Grapefruit Seed Extract). You can find it at any health food store. Maybe even the health food aisle in some larger grocery stores.
Follow the directions for diluting it and wash the wound well.
With our cats it normally only takes one cleaning and the abcess is gone.
What I think happens is: The cats lick the excess fluid away after treatment, ingesting the GSE so it not only is working topically but internally. The bacteria causing the infection is killed both ways and the abcess goes away much quicker than with peroxide. We LOVE it and use it for all sorts of things.
Do a search to find out more but basically ...
"Grapefruit extract is used as an antibiotic, antiseptic, disinfectant, and as a preservative in food and cosmetics. GSE is also non-toxic, environmentally safe, and quickly bio-degradable. It causes no side effects and is often dramatically less expensive than existing treatments or chemicals for similiar applications, whether human, animal, or agricultural in scope."
Mary Ann