Need to make a concrete floor non skid for a horse?

I am in a pinch. We jsut bought this farm and until we build a big barn we have to put our horses in a mechincal shed with a concrete floor. The concrete floor is smooth and the horses with their shoes will no doubt slip and slide. My question is what is the best recommendation for turning a slick concrete floor into a not skid floor. That I can perform myself. Where can I get the equipment with out hiring it done. It is only about 20 by 40 floor so it can be done in a weekend. Let me know your thoughts and ideas would be welcome. With in reason.