Prior to her second heat cycle, her risk is still only 8 percent. (texvetpets.org)
After the second heat cycle, there is no significant impact on her risk by spaying. (texvetpets.org)
Female Dogs: Spaying female dogs (called ovariohysterectomy) prevents heat cycles from occurring approximately every 5 months, and if performed before the first or second heat cycle, lowers the chance of mammary cancer. (puppy-basics.com)