Zina, our 10 year old Jack Russell Terrier will be 11 in November. We adopted her from a shelter last February. She is not spayed which somewhat unusual for animal shelters. She was examined earlier this week and given a clean bill of health. There are many discussions going on about the high risk of contracting Piometra in older bitches. There are many in favour and just as many against. I would really welcome your opinions, thank you very much.
We have an old unspayed female. Like 14-15 years old. She's never had reproductive issues at all (no bladder issues either) but she's always had horrid issues with mammary tumors. They say spayed females very rarely get these, so I always stand behind spaying females at an early age. However I can't say I would do on an old dog for no real reason. If it ain't broke, don't fix it. Pyometra is bad IF your dog ends up with it, but it isn't extremely high risk to where you need to take preventative measures in a healthy dog IMO.
I have always had my bitches spayed at 6 y o. My daughter has a terrier which did develop a pyometra last year - I think Elsie was 8 or 9 y o. However, your girl is eleven, does she still come into season? As @Malka has suggested elsewhere, it would be better to make this decision with your vet, who would be able to advise on the relative risks in your particular case.