My sweet sweet Anna was a rescue. I had her for nearly 2 years before I had to put her down a couple weeks ago. She was never fixed and by the time I got her, she was 9 years old and already had some masses forming. I feel very strongly that if you are not going to breed, a female should be fixed asap. The vet said those masses are caused by her having too much estrogen being produced during her heat cycles and with there being nowhere for it to go, so it formed huge masses in her mammories. Some where benign, in the end, some where not. It was the most devastating decision I have had to make.... Don't know if that helps you make your decision or not. (She had been bred before I got her)....
"Be a best friend, tell the truth, and overuse I love you
Go to work, do your best, don't outsmart your common sense
Never let your prayin knees get lazy
And love like crazy"