We got this so our cat can't get in. So far so good. We leave it open when when we're watching him, but if we walk away for a moment we close the dome cover so the cat can't get in.
Fisher-Price On-the-Go Baby Dome, Grey/Multi-Color [Amazon Exclusive] https://www.amazon.com/dp/B071XC6Y64/ref=cm_sw_r_cp_apa_gTa.Bb4088SNP
I recommend this: Fisher-Price On-the-Go Baby Dome, Grey/Multi-Color [Amazon Exclusive] https://www.amazon.com/dp/B071XC6Y64/ref=cm_sw_r_cp_api_i_q5SvDbHMG509F
It keeps the baby covered and it is safe for overnight sleep.