Greetings,
'Spaying your pet before her first heat (that is, before she reaches sexual maturity) greatly reduces her chances of developing breast cancer and completely eliminates the threat of uterine and ovarian cancer and uterine infection, which are common occurrences in unspayed females. '
--- This is a quote from the pet benefit league. If you go on google.com & do a search for "benefits of spaying," there are all sorts of statistics to support this statement.
My Yorkie was spayed around 7 years old. She had several litters and eventually developed breast cancer-- all before she came to live with me at 8 yrs old. I had more health problems with her than any other bitch I've ever owned.
Around Feb. of each year, she would have a type of false heat. Tail crooking when males came up to her, be inviting to the "boys" and her personality would change. I never noticed this from any of the other spayed females I've had. But their surgeries were done from 4 months- 1 yr. Not as late as hers. Oh btw, she loathed puppies.
I don't know anything about immature females who should have matured before being spayed. Mine have all grown into adult behavior after their surgeries. But I've never had golden retrievers. Compared to wild dogs & wolves, our dogs are perpetual puppies anyway. It can also be that individual dog that would have ended up the same way regardless of her sexual status. Who knows?
I firmly believe that if you desire only a pet and that you aren't interested in the work that goes into proper breeding & showing, spay or neuter your canine. Health & sanitary reasons make it easier to decide this.
good luck with whatever you decide. Just love & enjoy your dog.
toodles