I've noticed a couple of times in these messages that people talk about vasectomising male cats rather than castrating them. Is this just a confusion of terminology? A vasectomy means a sort of tying off of the vas deferens (the tube carrying sperm from the testicles) and certainly a vasectomised cat will not be able to get a female in kitten, but if the testicles remain (castration means removal of the testicles) then the cat will continue to exhibit all the normal and usually unwanted tom cat behaviour because it is testosterone produced by the testicles that makes them behave this way. Could someone enlighten me? Thanks.