Well, the method varies for each product. Most times, a cat litter mat only needs a change of the stuffing and a wipe with a clean cloth and antibacterial solution. Some other products follow a different lead. You may have to move them and dust them with a dry cloth. If the litter is heavier, you may need to vacuum it out of the mat. The best-case scenario would be if you can soak the mat, or chuck it into the machine, but only if the manufacturer allows it. Not all mats are machine washable.