J.O.
You can sanitize the sand, sand can get expensive to replace. I know and have run into this problem a time or two. Ideally dumping and starting over is best, but if there is a problem, it's not just going to go away because you have replaced the sand.
Bleach, 1/2 and 1/2 ratio of bleach and water in a sprayer. First spray the top layer, mix it up and spray the next layer and repeat till you are certain that you have gotten all of the sand. Then let the sun dry it out. Good to go.
One way to stop the little kitty's is to use a motion sensor sprinkler in that area, kinda like people do when they have a problem with deer. I know there are some essential oils that can be sprayed around the area, there are some animal repellents out there and even some plants that work, but I don't know which ones off hand.