How to treat an abcess. Never dealt with one?

Get your vet to remove it. They can become serious over time if not attended to. Your vet will give you bute to give your horse to help with the pain. You have to soak the foot in epsom salt and water everyday or every other day and then wrap the hoof in gauze and duck tape. You are absolutely right about treatment but I would have the vet com out and pop it ASAP since it can be very painful for the horse. Good luck!