I agree with the feliway - I have just been looking after a neighbours 3 cats and one of them was clearly upset and spraying after I picked him up. I was concerned that the smell of my own cat was causing offence, so the next time I went 'round, I washed by hands and sprayed feliway on them and the bottom legs of my jeans (same ones as before). I also removed my shoes as the sound seemed to scare him. It worked a treat and the cat was completely at ease - amazing stuff!