I want to add something on top of my garden fences to try and deter cats/foxes in my garden. Ours is the only one with grass/mud around here so we have a queue of cats using it as a toilet and I’m fed up with cleaning it before my children can go outside. They will run if they see me so this usually happens when I’m not home so water guns etc are no use. The options I have found is trellis - am I allowed to add this on top of the 6 foot fences including neighbours boundary? Fence spikes - again can this be added on neighbors fence and is it legal eg if neighbours claims they cut themselves on it? I’ve also read about nailing foil to put them off walking across. Lion poo didn’t work. Any advice or tips would be appreciated!