The only thing that I know of that really works, is there is a plant that repels cats and dogs. I bought it last year at Walmart but saw it at several garden centers. It was labeled Scaredy Cat, Dog's Gone and Bunnies Gone. It smelled a bit like a skunk when I touched the leaves. The official name is Coleus canina Sumcol. I planted two, one in each place that the neighbor cats had been using as a box. The cats never came back to those spots.