I dunno Ratie, I think I might be tempted to point out to them that, having taken on the animal they now have a responsibility to care for it. It has done the work that they wanted of it, so it is entitled to a little superannuation - in the form of a decent home. Also, if they get rid of it the mice will come back and they will need another cat - so they might as well keep the one they've got and look after it properly ... As you say, some people just shouldn't be allowed to have animals ...