I like Edwina's Sec's idea. It's true that sometimes people become defensive when others try to give them advice. Maybe if you made it seem like you did some research for your own information and just thought you'd share it with her she might be more accepting.
My cousin has two poodles-male and female-and I am constantly trying to convince her to have them "fixed". She insists that she can just keep Sasha locked up in a room while she is in heat to keep Brian away from her. Sacha has already been "with child" twice, so it's obvious that this idea is not working, but she still has not taken them in. I'm still trying to convince her, though. It's tough trying to talk some sense into hard-headed folks.

Edwina's Sec-I'm the one who posted about depriving cats of a sex life. In one of the books I have about cats, the author claims that cats should not be spayed/neutered because this deprives them of a sex life. According to him, they should instead have tubal ligations/vasectomies so that they don't lose their natural desire to mate. I thought this was strange and posted about it to get everyone's reactions.