Mmm Abscesses on 2 cats?

My neighbors seem to think that because I'm in college to be a vet that must mean I know how to treat everything, even though it's my first year. Anyway they called me over, two of their cats have abscesses. One on orange cat's leg and the other on black cat's stomach. They refuse to take the cats to the vet, though I give them credit for getting the cats fixed at the shelter tomorrow. They had the abscess on the leg bandaged and the other free. I cleaned up the pus and blood the best I could so to trim the hair around it to let everything drain out. Is there anything else I can do for the cats? Maybe give them some kind of meds I don't have to get from a vet. I have my own cats to worry about really, and I can't go spending $30+ on someone else's cats when I don't have a job. Also, I can't "liberate" (cat-nap) the cats because they're inside cats now I believe. Anything I can do for them?