What do you do about a lame horse?

Hello. Since Monday is quite a way off, I would do two things. The first is to call your vet for advice. The second, if you suspect a hoof abscess, is to apply a warm, wet poultice to see whether it helps draw the abscess out.

If your horse is avoiding loading the sore leg, it is a good idea to put a support bandage on the other one to prevent overloading. If he is so lame that he cannot stand, you should definitely contact your vet, unless the farrier can come sooner.

Good luck!