My dog will not look at herself in the mirror. Other dogs act cute and try to play with the dog in the mirror. My dog will not look and will not react to anything in the mirror.
The dog I grew up with (a Shih-tzu) never paid any attention to mirror reflections or the television. Being proud owners, we chalked this up to a sign of extreme intelligence. 
Most cats see themselves in the mirror, and recognise there’s a cat there, but eventually realise that it’s not a normal cat. I once watched a kitten see itself in the mirror for the first time, and it was very startled, because it did not think there was another cat in the room. So, if a dog is not reacting at all to itself in the mirror, it must have worked out that it’s not a real dog in there, and is just ignoring the image.
I’ve always assumed this was because there’s no scent coming off the mirror dog. I don’t know if that’s a realistic explanation, but none of the dogs I’ve had ever reacted to a mirror or to dogs on TV.
Dogs do, however, seem to react to the sound of other dogs on TV or the like. I assume this is because they can hear from a greater distance than they can see clearly, so it’s plausible in the wild that a dog might hear another dog without being able to see it.
Dogs/cats can certainly see themselves in a mirror and as noted sometimes they will react thinking there is another dog/cat there. In general though they twig to the notion that it is some sort of trick and learn to ignore it.
Some consider this a sign of animal intelligence. IIRC only humans, chimps (or some of the great apes, I forget) and dolphins recognize the image in the mirror as a reflection of them.
I have heard, do not know if it is true, that you should not put a mirror in a parrot cage (or other type of bird who mimics). Supposedly the bird will see another bird so stick with bird-talk. When no other bird is “present” they decide to mimic the people around them and “talk”. Dunno if that is true or not though.
Maybe she’s ugly.
The stuff I read said it’s bad because they’ll think the mirror bird is a potential mate, and get cranky when mirror bird won’t respond to their advances.
Elephants also recognize images. I saw a documentary once of a painting elephant, who could paint a picture of an elephant.
From my experience the youngs ones tend to be interested in the mirror dog/cat but eventually they figure out it is not real. I think not being able to smell the other dog/cat is what starts the process.
My younger cat who is two likes to play patty cake with himself in the mirror. He’ll sit up on his haunches and continuelly swipe at his paws in the mirror. He’ll paw paw paw paw at the mirror and then stop and look at himself and then paw paw paw paw some more and then look at himself. I think he knows it’s not a real cat because any other time he ignores the mirror cat.
The painting elephants are taught to paint elephant shapes as it gives the owner-trainer cash and fame. Does a Video Show an Elephant Painting a Picture of an Elephant? | Snopes.com
For what it’s worth, my cat has absolutely no reaction to seeing herself in the big hall mirror. Not that she looks anyway. If I pick her up and put her in front of the mirror, she doesn’t give it a second glance as she tries to get away from her weird human.
I swear my dog had some concept of the purpose of the mirrors in our house. I could talk with her facing away from her, and if she could see my eyes in the mirror, that’s what she would focus on. It was kind spooky, especially when she’d do it when I was some distance from the mirror.
Even if the painting elephants can’t recognize what they’re painting as “an elephant” (and I’m not sure how you would even test that), they can at least recognize it as “the thing I’m supposed to paint”.
Most dogs I’ve associated with seem to ignore sounds of dogs on TV.
I’ve heard of dogs barking at the sight of other dogs. I always found that curious because dogs don’t really seem to get the concept of pictures…do they?
That’s not quite what it seems. From Snopes:
In other words there’s no evidence that the elephant recognizes the painting as an elephant at all, or indeed as a representation of anything. It’s doing what it’s been taught to do.
Of my 7, three of the dogs react to barking dogs on TV, none react to a mirror. One will actually try to get to the dogs on TV, even non-barking ones. Last night she saw a tiger and went bonkers.
My dog used to park at herself in the mirror, she eventually stopped doing it and now ignores it. My other dog would watch TV really serious when he sees a dog on there.
It’d be even spookier if she didn’t. Since dogs don’t understand language well enough for anyone to tell them that mirror images are two-dimensional, they still correctly understand that the image in a mirror is three-dimensional. It looks just like a person, unlike a two-dimensional photograph or the like, so it’s only natural that, to the extent that a dog reacts to visual stimuli at all, that it should react to an image in a mirror in the same way that it reacts to real things.