Thanks for the responses. After the vet visit we'd tentatively scheduled an appointment for surgery on Wednesday. On Monday night, he was full weight bearing again, the next day, the swelling was down considerably and he felt near normal. Today, the swelling is barely noticeable upon palpation. I'm not sure whether I should be kicking myself for not getting it removed on Monday, when I had a chance the vet would find it because of the swollen lump, or if I should be happy because he's feeling so much better and hope the quill isn't pumping its way up to his heart/lungs. Yikes. That is so scary.
I also wonder, though, if the vet would have found it had she cut the thing open. It's a catch-22, as feet are full of tendons and arteries, with really NO fat on top where the quill was (I'm not sure what the foot pads are made of)- so one bad cut could, I would think, cut something very important.
I'm going to wait on this one, and then, this weekend, go off and try to get that porcupine aversion training in once again. Thanks for the advice. I had a good country vet where I lived last, charge $200 for a laproscopic spay- I can't understand how a quill removal could then cost $600? If this flares up again , I'll be looking for a less expensive vet- and I'll get that thing out.
Thanks for your concern. He seems perky and happy.