My mom told me about a hint she read in a magazine (can't find it on the net anywhere but it does work, I have done it). When I first moved into my trailer there was a stray cat that was marking my door, porch & shed.
Take liquid fabric softner and dilute it with water (I can not remember how diluted it has to be though, this was a couple years ago) and spray it around your house where the cat(s) mark. I just used cheap fabric softner I think it was about half water half softner (maybe just a little more softner?)
Not only did it remove the odors but it repelled the cat as well.