We don't go to zoos of that type, either, so that example doesn't work for us :)
We do our best to not put our money toward operations which indulge in that sort of practice. I know it may seem weird to some, but we accept that as a result of exercising our prerogative.
I'm not sure explaining it would help you to understand, as I'm better at just attempting to live my values than trying to convert others to them, so I hope you'll forgive me for not trying to make it more clear. If you'd really like more information and that doesn't do it for you, let me know and I'll give it a try.