I've had 30 cats at one time (I got "volunteered" as the rescue home after Pet's Fate closed it's doors in our town) and had only 1 cat (a spayed female) that sprayed. After a check-up with the vet, and no health issues could be found, the vet believed the cat was naturally high-strung and wanted all the other cats to believe she had the right to all the territory. In other words, it was her way of responding to stress. She was given a medication, sort of the feline version of an anti-depressant, for use only when she showed signs of stress (spraying), and she was fine after that. Unfortunately, that beautiful Calico passed way and I miss her dearly. If a vet told you to put the cat down for spraying, I'd find another vet. If you don't want to go the chemical route try cat-nip....even though it is a stimulant for cats, once the craziness wears off, they calm down quite a bit. I always give my cats (I now am down to 6) a little before having to travel and they end up sleeping the whole trip.