We unfortunately had a more traumatic experience for our kids when my first cat, Luna, died. I found Luna in the basement under the workbench, unconscious and barely breathing. My wife held Luna in her lap while the kids (2 and 4 at the time) got to pet her and say goodbye. Luna died while we were all petting her. Our 4 year old was extremely upset for weeks after, and we ended up getting her a cat stuffy that looked like Luna to help her cope. Our younger kid has zero memory of it happening.
All of this is to say, I would not recommend having your 4 yo present, but do give him the chance to say goodbye in his own way and make sure he understands that your cat will be gone forever.
We unfortunately had a more traumatic experience for our kids when my first cat, Luna, died. I found Luna in the basement under the workbench, unconscious and barely breathing. My wife held Luna in her lap while the kids (2 and 4 at the time) got to pet her and say goodbye. Luna died while we were all petting her. Our 4 year old was extremely upset for weeks after, and we ended up getting her a cat stuffy that looked like Luna to help her cope. Our younger kid has zero memory of it happening.
All of this is to say, I would not recommend having your 4 yo present, but do give him the chance to say goodbye in his own way and make sure he understands that your cat will be gone forever.