My parents returned my Layla to the shelter, she was at the point of insanity, she was mentally unstable, and we should have never adopted her in the first place.
EDIT: when I was 9 my cousins moved to england and I took care of my cousin's hammy. (named Hammy, I was sooo mad at his for naming him that)
He was about 3 when he developed a cancerous tumor. My mom took him to every vet she could go to and they all said he was too old to have anethstisia for the surgury so we finally euthenised him My mom was bawling all the way home, she could barley drive. The vet sent us a simpathy card the next week because he was so worried about my mom.