I only allow students that I absolutely trust to take our animals home, and I only let them take the animals home over breaks when I will not be around to care for them. My best advice would be to write a care contract and have the students submit an application that their parents have signed. That way you know that the parents are okay with the animals coming home, there aren't any existing animals at home that may pose a threat, and that the student is capable of caring for the animal. I hope this helps!
I have a letter that has been reviewed by our school attorney that the students and the parents sign off on.