
You really need to ask people about their own experiences, as most of the evidence is anecdotal - vets tend not to pool all their clients' animals records, and some possible side-effects don't show up till years later. As a general rule, my vet advises that bitches shouldn't be spayed until they are reasonably physically mature, ideally not before their first season. Smaller breeds seem to be okay spayed earlier than the giant breeds, which in some cases don't mature enough till they are about 18 months old. There is no hard and fast rule, I'm afraid, but try not to worry. It's perfectly possible that your bitch will live a long, healthy happy life with no problems, but no one can ever
guarantee this.
:)