I agree with Stacwase, it does look pretty nasty and needs to be looked at asap. If it is an abscess, it most proabably would be lanced and as Stacwas said, perhaps a drain would be put in; definitley antibiotics would be in order, I'd think. I have experience dealing with abscesses in human patients, but not dogs. I know it's costly to be seen on a weekend, but I'd definitely take Bongo in today if at all possible. The sooner you get him treated the better and you'll have peace of mind. How's he doing today?

P.S...Bongo's a cutie