I’m surprised that the owner didn’t want to be with the dog to comfort it as it passed.
Putting down a family dog can be very tough. I could see someone having great difficulty facing it. I am trying to be charitable here.
Putting down a treasured member of your family isn’t for the feint of heart. I held my dog while they administered the injection and then proceeded to wail like a banshee when she was gone. They had to usher us out the back door cuz I was so distraught.