I'd let it go. I know people who don't like cats or dogs or whatever. I just ignore it and move on. Now if they make comments about it all the time, I'd probably just constantly make comments about how much I love my pets. Just to throw it back in their face.......in a nice way, of course.
I have a co-worker that doesn't like dogs and cats. She doesn't know why, but she has bought me a kitten calendar the past two years for my cubicle. She asks about them if I mention they are sick or injured. But she'd never own one herself. And I have another friend that is petrified of any animal. She saw her mom get bit by a dog when she was young. But we still got along great!
I guess what I'm saying is she should respect your opinion and views on liking animals just as you'd respect hers on not liking them.