I've had to go through 2 dogs being put to sleep. The first was a Cocker Spaniel, she was the dog of my grandmother's friend who had died. We kept her for about a year, but she started to go blind so we had to put her to sleep.
The second was a Beagle named Buster. I had him since I was 2, but at the end of 9th grade he got really sick and had to be put to sleep. Me and my parents went to the vet when he was being put to sleep so he knew we were there.