[gracielove]

She is not too old to have problems with surgery. Why keep her intact if she is not a breeding female? What is the benefit? Saving money? Spaying would spare her the continual heat cycles and spare you from having to clean up after her and being extra careful in watching for male dogs she could attract to your area. Male dogs can smell a female in heat for miles around so there is always a danger of a male getting loose and coming to find the female.
The constant hormonal shifts does increase the risk of cancer when she gets older. When she is older you may have more of a risk having her go under anesthesia. So waiting until she is more at risk is not a good idea.

I had a female almost die of a uterine infection during a heat cycle. There are more benefits to having the surgery done than not to.