Oh man. I am so sorry. I know what you are going through though. We had a part Pekenise/Yorkshire Terrier mix that we had to put to sleep when she was 17yrs old because she had gone deaf, blind, and had arthritis......she was just suffering.
I hate it when this happens, but it's better to end their pain than to let them go on like that.
<great big hugs to you>
