...a 15month old GR who has not yet had a season.

"Wait until 3 months after first season", has always been my "rule".....but now I'm wondering what if she doesn't have a season or she's 2 or 3 years old before having it?

Can I have your thoughts please?
Thanks

this might be useful , there are other articles around with similar conclusions. personally I wont neuter before fully mature unless there are health reasons If she were mine I would leave until fully mature if you decide to spay
I have 5 yearold, flat coat who was like yours and only had 3 seasons in 5 years when I had her spayed laprasopically

I agree with waiting until at least 2 years old to allow growth plates to finish growing. She will need those hormones for her growing joints, and also for her to achieve her full potential. Many pups her size done too early where the head and body aren't in proportion because dog was still in growing stages and never finished due to lack of hormones.

Almost there at 15 months so might be worth waiting a few more :)

Although u will be told about possible cancer risks that can be avoided by spaying what u often dint get told is that there are  many more cancer that can occur due to spaying and that a lot of  these are  malignant and difficult to cure . The other issues can be behavioura problems

I'd still  wait as she obviously  hasn't  matured yet.

I always  advise between 2 nd and 3 rd.

There is no problem waiting, as the health risk factors are directly linked to the action of the seasons. No seasons so no worry.

I always wait until after the second season, whatever age that happens at.
I've no males in the house so don't need to worry about accidents.

I bet you she will have had her first season by 18 months. Happens to a lot of my bitches.

I wait until mine are mature, usually around 3yrs old and so far, it's always ended up happening after the 3rd season or at least been planned to - Willow's just had her 4th because one of my others collapsed the day before her op so it had to be cancelled.  But she will be done this time come hell or high water!

Up to the time we bought a Whippet, our Bassets had all been spayed on being retired from the whelping box.   I did have one who came in, unexpectedly bang on 6 months and then started cycling every 5.    She wasn't as good as I'd hoped (singleton puppy at that) so after three seasons doing that, I had her spayed.    I talked to my then vet about having my Whippet spayed before her first season as I had an elderly entire male Basset at the time, and he wasn't a well boy and didn't need to be around a bitch in season even if she'd have been in another part of the property.   That vet advised me to let her have one season before being spayed, citing bone development problems, potentially, and spay incontinence possibly too.    I backed off, and made arrangements to have her boarded in a local Kennels when she came in.    However, by 11 months there was no sign of a heat - talking to her breeder she said her half-sisters didn't come in until around 15 months for the first time.   As her growth plates should have closed by that time, I asked my vet to go ahead and spay, which he did and at coming up to 8 now, she's fine - maybe a touch taller than she might have been but that could be her genes!

I think I might go ahead before the first season with a small bitch, but provided you can confine her when in season the first time, let her have one season before being spayed.

Fully mature in some breeds could be 2 ... 3 years even and you should factor in the more seasons a bitch is allowed to have, the greater, increasingly, the risk of her developing a female-related cancer or pyometra.    One of our older-spayed retired girls did develop mammary cancer and that's some thing I'd not wish on my worst enemy.   But she was only one of a lot of bitches we've had.

I have a tiny breed.  Very much smaller than a GR    And I have mine done at 4 years old.

It's always emotional for me, answering this. I lost my much loved girl far too soon through ovarian cancer.  I have researched it intensively so know how very very rare it is. I only discovered it when I took her to be spayed at 8. I would have spayed her 2-3 years earlier (which could have saved her) were it not for other 'stuff'.
Having said all this, I still wouldn't spay a bitch until at least 3 years as there's so many other, more common, cancers bone deficiencies obesity diabetes etc etc linked to spaying.  
The only cancer showing reduction in early spay is mammary and, as Brainless said that is related to how many seasons and I suggest is more easily seen, never mind diagnosed, than such as bone cancer. I
I strongly recommend you do lots of your own research and join

https://m.facebook.com/groups/457912764294115?ref=bookmarks

60% of mammary tumours are benign, and early diagnosis ant treatment of the others is curative.

I have now owned 11 bitches of 17 months plus, of these 5 are deceased and 4 over 5 years of age. 10 are of my current breed.

Only encountered tumours in one at 5, then recurrence at 11 when a partial strip performed. Death at 13 1/2 not related.

All my bitches have remained entire until at least 5 more often 7.

Thank you all for your advice and also for putting my mind at rest about the subject.   More patience required!