Update on McGriff:
The vet saw him today; they're going to keep him overnight to run some tests and also get X-rays to check for fractures, blood clots (he had reduced circulation in both hind legs), or anything else abnormal; he was very dehydrated so he'll get fluids to correct that as well as a blood thinner to hopefully deal with clots that aren't too bad.
EDIT: We had to put him down yesterday
He was in severe congestive heart failure; his lungs were building up fluid, heart was throwing clots and we could see he was struggling to breathe. We saw him in a private room and he was growling, hissing and trying to claw us which he never, ever did. Even the vet said a referral to the big hospital would only put him through more pain which we just could not do. There wasn't a single dry eye in the clinic.