Well, sweety, I know this may not be what you want to hear, but....She's thirteen years old. Maybe she went away to be alone so she could pass away. My dog, Suzy, did that years and years ago. She was old and got out one night. She found a place to hide and she died. Although it's not something we want to have to go through, maybe it was just Mitzi's time.
On the other hand, if that's not the case, I hope you find her safe and sound. Give her kisses and enjoy your last years with her. My golden retriever was 15 years old and just passed away in November. You will cherish those last moments.
I'll pray for you!!
