OSS-Ovary Sparing Spay

Wellll... there's the first inkling of signs of a change of attitude coming down the road when it comes to full ovariohysterectomy, or just hysterectomy (OSS).
There has been a meta analysis carried out which investigated the research to date on the risk of various cancers associated with leaving a female hormonally intact, particularly in relation to mammary cancers, and it turns out we've been kinda sold a pup in relation to the level of risk. It's nowhere near what was previously thought, based on the research available.
In addition, another thing that's coming down the line is the very real risk of spaying females at the wrong time of their cycle, which, it turns out, is almost all of it. The conventional advice has always been to spay mid-cycle, so... 12ish weeks after the start of their last heat. The problem with this is that all females go through a pseudopregnancy following heat... many of them show no or few behavioural symptoms, but hormonally, they are all still in pseudopregnancy by the time the conventional time of spaying comes around at mid-cycle.
The risk is that if you spay them now, with a full ovariohysterectomy, you will put them into a state called "persistent pseudopregnancy". The symptoms fall into 2 categories.
The first is an almost immediate appearance of aggressive or anxious behaviour following the spay.
The 2nd is more insidious... the appearance of aggressive or anxious behaviour long after the spay (weeks or months). In this event, because it's insidious and happens so far after the spay that the connection is not made, owners often don't take action for some time, so it could actually be a couple of years before they seek the help of a behaviourist, rather than their vet.
If a female does get stuck in this state of persistent pseudopregnancy, the treatment is very straightforward, and works very quickly... it's a hormonal treatment which restores the hormones to where a spay is meant to leave them.
To avoid this risk of persistent pseudopregnancy, there are a few options.

One is to spay before the first heat.. but this, we now know, brings its own significant potential health issues re joint development, cancers, and an the underrated effect of potentially compromising psychological development.

One is to perform an OSS, so that the reproductive hormones can cycle normally and without interruption, in the knowledge that the risk of traditionally associated cancers is significantly lower than has been thought.

One is to leave the female intact.

One is to carry out a full spay, but... and this is hugely important, it must NOT be done mid-cycle as per traditional advice. To allow the hormones (specifically prolactin) to reduce down to very low levels, a period of 19 weeks must be left from the start of bleeding in the previous heat before the full spay is done.
This is going to make vets itchy, because it's getting very close to the next heat, and it's not advised to spay in the 4 weeks leading up to the next heat due to the proliferation of blood supply to the reproductive organs.
That leaves a window of opportunity of only a couple a weeks for a full spay to be done such that the risk of persistent pseudopregnancy is avoided, and at a time when it's safe to do so from a surgical perspective.

It is not yet known what proportion of females are at risk of persistent pseudopregnancy.
It is not yet quantified how many females have been put to sleep in the past with seemingly incurable aggression that appeared quite suddenly and out of character.
It is a message that hasn't got out there into the wider audience yet, including vets, but like many other game-changing research (eg Rottweilers, early castration, and osteosarcoma), the word will presumably get out with time. There are already veterinary reproductive specialists in the UK who will not spay females before that 19 week period has passed, or at the very least, will make absolutely certain that there isn't even a hint of hormonal activity associated with pregnancy, before they spay. These practices are also aware of how to treat persistent pseudopregnancy should it, or anything resembling it, occurs in the days, weeks, months or even years following a mid-cycle spay (or a spay that was carried out at an unknown stage of the cycle, eg rescues).
Food for thought. You possibly heard it here first!