Yes, uterine infections are a real risk with an older female. I have a 7 yr old female that's never been bred, she's just a pet. I am getting her spayed next month since I don't plan to breed her and at age 7 she's getting older. The risk is significantly higher for older females that have never been bred. I'd rather not risk pyometra so feel spaying her is the best choice. She was from a litter of 11 pups so some of her siblings can carry on the line.