I am glad to read the story of Ms. Charlotte. I would bet that she has tons of character considering all that she has been through and is still a loving and joyful companion. May I suggest that you use the best information available to you and assign her a birthday. She deserves to have a birthday. I have three rescues of different breed mixes and different ages. I rescued each one as a puppy and with the expertise of my vet, their approximate ages were determined. I would then count backwards over as many weeks or months there age was determined to be and assign them a special birthday. For example: We figured one of the them was probably born in July, so I gave her a birthday of July 4th...that's special and easy to remember too. SPECIAL NOTE FOR MS. CHARLOTTE: You are beautiful on the outside and I'm sure you are even more beautiful on the inside. May you have many years of love and happiness with your forever family.