The people in our performance dog club, most of them training and competing in agility, were some of the first ones decades ago to jump on the wait bandwagon.
Not that there were that many injuries, but we didn’t see any less injuries in those than the neutered ones.
Neither incontinence, a friend’s not spayed golden had several orthopedic surgeries and was on medication for incontinence and was spayed later.
I think that, if there is a difference, it is extremely small, not worth the chances of pyometra, breast cancer increases with letting puberty come on strong first before spaying, as someone said, the management of a female in heat can be hard on a pet household, plus the chances of unwanted reproduction.
There is one breed specific situation in dalmatians.
Un-neutered male dogs may grow a larger urethra if not neutered.
That is a breed known for urinary crystals, where that may be a concern.
At least that is what at one time dalmatian breeders and their vets were pursuing, don’t know if it is still determined it is so.
In horses, gelding before puberty, that generally happens around 18/20 months, about the time knees and hocks growth plates close, has been known to let horses grow that extra 1/2" in those six months that process is delayed thru gelding.
Not in all colts, but enough to be “statistically significant”.
Does that alter their genetically predisposition to a certain skeletal length proportions, is that harmful in any way, or does the body adjust seamlessly to it?
Does in the dog?
Some studies want to say yes, the changes are not always easy to adjust to, here are statistics saying more early neutered dogs have injuries.
Maybe it should be, not sure yet, lets do more studies first before deciding why the injuries?
I think it is not wise to make a blanket determination against spaying before puberty for all dogs and their owners, as some insist is “best”.