I would NEVER leave any dog or other pet to be euthanized. I would never leave them in their last moments with strangers. The times that I’ve had to do it, I’ve held them in my arms, and spoken quietly to them. Then I take them home. I did leave one with the vet for cremation, but I’ve never done that again. It felt wrong.
I’ve stayed for the ones I’ve had to have euthanized (last 2 have died on their own and I”m thankful for that). But I have had mine cremated. I know it may or may not be their ashes I’ve gotten back, but we have not lived in the same place all alone, and so I didn’t really want to bury them somewhere and then leave them either. So, I have carried these little boxes of ashes around. I really have no idea what I’ll ultimately do with them. I have an Aunt who has a pet cemetery. I think I might put them there, or maybe we will scatter them wherever we retire. Not sure. For now, they reside with me. I guess it’s weird, but it’s mostly for lack of any other idea what else to do with them. They sure are heavy.