Won't put any weight on front paw

[SocialButterfly]

My gorgeous boy Casper has been limping all day, he won't put any weight on his front leg. He hasn't really moved all day. There is no obvious damage, I have vets appt in an hour but any ideas what he could have done and what the treatment might be?

Our cat was like this a few months ago. Turned out he had been in a scrap with another cat and had got bitten/scratched and it had got infected. Course of anti-biotics and a hefty vet's bill later, he was back to his normal bruiser self!!

Good luck at the vet's.

Thanks he does get in to scraps so it could be that! Just as well I've just been paid!