My mom used to be an advocate for children with mental disabilities.
She had been assigned a new family that month, and they seemed pretty normal. Both parents checked out, and the kid was about 10 years old. He had a moderate case of Autism and Schizophrenia.
The family also had a dog for the kid to play with. When the dog died, the parents decided to let the kid keep playing with it. No- they didn’t stuff it. The kid played with the dead dog for a couple weeks before my mom realized what was going on. The kid would even sleep with the dog at night.