im like so close to tears right now... maybe this will help you decide...
well my cousin lost her baby about 2 years ago. she told me she knew it was time when she got on the floor on her belly and looked into her dog's eyes and saw pain. she knew it was time.
i think if you see her not happy or in pain it might be time, don't listen to what i say but just think she will keep your mom company up there. it might be hard to see her leave, but i think you'll do whats right
HUGS