Thank you to everybody that has commented so far- I appreciate your input. If I do lance it and try to express the pus, I will use hydrogen peroxide to loosen it up, do a final rinse with a weak betadine solution, and squirt some Nu-stock in it (Great stuff, huh, Jack? I've not used it for abscesses before, but it did get rid of Hub's athlete's foot!), and give him penicillin injections.
I've been up since 4am, and have been researching pastuerella and abscesses, and the prognosis is pretty poor, I think. Unlike dog and cat abscesses, which is where my expertise in the field lies, rabbits form a very thick pus with a toothpaste like consistency... one veterinary site showed what appeared to be a solid lump of it from a pastuerella case. The incidence of recurrence is very high, since the matter is very hard to remove, and there may be a finger-like tract leading elsewhere also filled with pus, and often the tissue of the abscess "wall" is infected and needs to be excised. Somehow I doubt Floyd will let me excise the walls of the abscess. (Ouch!!!)
Another factor is of great concern to me- in my research this morning, I found that pasteurella commonly presents as thick white mucous from the nose. When I picked up the rabbits initially, I noticed a very small blob of white mucous by his nostril. The breeder had traveled several hundred miles to our exchange point, and I had traveled 150 miles + myself... she said she would replace him if he died. He never progressed beyond that point, and after 2 days I never saw another symptom... but I fear the infection went dormant, and the stress of the show has caused this flare up. I realize that pasteurella is commonly believed to be carried by all rabbits, or at the least that all rabbitries have been exposed... so I am not laying blame anywhere... but it seems the best protocol is to cull any rabbits that succumb to infection and only breed those that show a strong resistance to it.
I was going to aspirate it yesterday afternoon to see if it was bloody fluid, and if not I intended to cull him. I met with great resistance from Hubs and the pups. Floyd is Hub's rabbit, and he and the pups were shocked that I could be so hasty, and not even "give him a chance". <Sigh... I am an ogre.> It was getting late at that point and I was afraid I'd lose light before I could finish, so Floyd is still safe for now. I didn't aspirate it because his isolation cage wasn't ready, and I didn't want to possibly spread infection.
I continued working on his hospital cage- the floor wire had two patches of rust to be scrubbed off, and the cage is going in the chicken run, so I had to figure a way to hang it safely, and protect it from wind and rain/snow. (We are supposed to get rain today.) It's hung now, but I still need to finish up with the protective panels. It got too dark to work, and my "trouble light" seems to have died. It is still pitch black out, and the wind is howling, or I would be out there already.
I am still leaning toward culling him to be safe... when the rest of the "pack" wake up we will discuss it further. I would also appreciate further comments from all of you regarding the decision to cull.
Thanks, everyone.