I have plastic crates. Adele has escaped from a wire crate and gotten a deep gash on her leg which required stitches, but she has never been able to escape or get hurt on the plastic one. Needless to say, I don't use wire anymore because I think it's too much of a saftely risk for Adele, so we have 2 large plastic crates (for Vallis & Adele- Marta is gated) and they have slots for ventilation, plus since they are confined we make sure to always have a fan on them in warmer weather.