it didn't take her to realize that it was her.
You're anthropomorphizing. Household pets lack the acuity it takes to recognize it is they which they see in a mirror. They do, however, have the sentience to realize the image in the mirror is not reacting to them and is no threat to them, thus why they stop "fussing" about the image they see there. They realize it makes no sound and has no smell that indicates it's a creature about which they need be concerned.
To be sure, Diamond does see something in the mirror. To tell whether Diamond realizes she's seeing herself, shave a small patch of the hair on the top of her head and then observe whether she uses the mirror so she can see that part of her head in it. She will surely be aware that she's less warm on the spot you shaved, but will she realize that it's she she's seeing in the mirror is wholly different matter and level of cognition. Can you train her to look in the mirror to see the shaved spot? Perhaps, dogs can be taught to do quite a lot of things, but that's not the same thing as their abstractly knowing what they're doing and why, to say nothing of using tools, which is what a mirror and its reflections are to creatures that are self-recognizing.
Whatever dude, I used to have two dogs that played with the floor mirror every morning. Seeing each other in it, playing around.
And in what respect is that anecdote probative about the nature and extent of canine cognition, specifically their capacity for ocular self-recognition?
It has been established that
canines have olfactory self-recognition capability, but it's not been established they are ocularly self-aware, which is what they'd need to have to recognize that it is themselves, not something other than themselves, they see in a mirror.
It's not surprising that they self-cognizant in one sensory dimension and not in another. Most people would not, for instance, know themselves by smell or auditorily, though humans often recognize others by sound or smell.
