Read this comment from @morgansc within this post dated May 30, 2019, 7:49 AM. It answers your question. Ideally it is best to wait until age 24 months but no early than 18 months.
spaying 8 yo female
My Angie is 8 yo and we have date for spaying her on 1 of March. I am worried because her liver enzymes are not in norm. The vet says he is going to use gas and medications that are easy and fast to eliminate. Please, share your experience and thoughts about this.
Is the spay surgery medically necessary? Just curious. My only intact female was never spayed and passed at 14.5. (All my others were rescues and came neutered/spayed.)
@senjisilly no, it is not by medical reasons. We have a male basenji too and when she is coming in heat we have to separate them for at least a month. She is coming in heat 2 times a year. And I think is better for her just to avoid any eventual health problems with reproductive system.
@emilia May we know just why you have decided to spay her now ?
Unless spaying her is going to substantially improve her quality of life, I would advise against it.