Well, my old girl Jazz was 13 years when we decided to make the very difficult decision to put her to sleep. She had gone almost deaf, she was pretty much blind, she had 3 teeth left, and couldn't switch to soft food as she was far too sensitive. It was May 28, 2009 that she left us. And I made sure the night before was memorable.
I let her sleep on my bed with me that night, and I swear she was smiling all the whole time

I miss her every day. She was my dog growing up... She will always be missed so dearly, by everyone in our family.
Triton was very sad too. He wandered the house searching for his friend, but he never did find her

He hasn't had much dog contact since her death either, which I feel is very hard on him. I've taken him to the dog park which is 3 towns away (I live in such a small town that there is no area where dog owners can socialize). He was so happy, but all the dogs there were so much bigger!
One day soon I hope I can get another chihuahua friend for him.
Rest in peace Jazz, you are dearly missed.