My old dog developed senility. Perfectly healthy animal but her mind was going, e.g. she was highly anxious unless I was within sight. My vet told me it's time to put her to sleep when your memory of her is becoming completely negative and so is the quality of her life. We chose a time, and peacefully, she relaxed and fell into a deep forever sleep in my arms. Thank heaven for animal euthansia.
Imagine what your children thought the next time you told them "Bedtime, kids! Time for you to go to sleep!", lol!