Dogs are best known for how keen their senses are. You can often see your dog being aware of someone's presence before you are. This is why millennia ago, humans started keeping dogs nearby, as they make for awesome guards.
Even though most of their senses are superior to ours, when it comes to the dog's sight, they are a bit behind us. To put it shortly, their sight is inferior to ours, both in color recognition and details. You can say that they have a lower resolution when it comes to sight than we do. This means that they can't discern some details that we can usually spot quite clearly.
Take glass, for instance, whether in windows, doors, or even mirrors. Do dogs see it? How will they react to their own reflection?
Signs of Dog Seeing Glass
You have surely seen one or two videos of doggos being silly and not going through a glass door even though there is no glass in it. This would indicate that they indeed don't see glass. Still, if you do a quick YouTube search for humans not seeing glass, you will see a tremendous amount of videos where humans bump into glass doors. Judging by the videos, though, we are not very good at paying attention to it sometimes. Is it the same with our canine friends?
Here are some signs that will easily let you know that your dog can indeed see glass:
Alertness – When your dog comes close to a glass door, for instance, they will most likely become alert and assess the situation: Is there really a barrier there or not?
Head tilting – You will often see your dog tilting their head to one side, then another, when encountering a glass barrier. They supposedly do this to better assess the situation: the glass barrier, in this case.
Barking – Your dog might start barking. They will not bark at the glass, however. They will, in most cases, bark at an object on the other side of the glass that holds their attention, and the barking will indicate their interest to examine the object. The glass will be in the way, and their barking might be a way to try to get the thing that holds their interest (another dog, for instance), to come closer, or to let you know that they want the barrier removed.
Raised ears – If the dog is curious about the glass, raised ears will be a tell-tale sign of it.
Sniffing – Your dog might sniff the glass, as this lets them learn a lot of information about any object that they smell: what it's made of, whether it's a threat, food, or otherwise. Some dogs have even been observed licking glass, but nobody really knows why they do that.
When it comes to mirrors, your dog's reactions will differ quite a bit. Your dog will see its own reflection, but this doesn't hold the same significance that it does to us. Dogs will not look at the mirror and think about the shape of their ears or their height. When they encounter the mirror for the first time, they will react as if they are interacting with another dog.
History of Dogs Seeing Glass
Throughout history, dogs slowly got used to our lifestyle, and as they evolved closely with us, they adapted to our various tools and contraptions - glass being one of them. It seems, however, that they still have big issues with glass surfaces. This has to do with their vision.
Because our dogs' vision has evolved to help them in low light conditions, they are much more focused on discerning movement and seeing in the dark than seeing fine details. This is why dogs might have issues with completely colorless glass—you need to pay attention to details to actually see it. Many of our fellow humans tend to fail to notice glass with their superior vision, too!
Other types of glass, like mirrors, tend to evoke various responses when first encountered, but as dogs are highly adaptive to their environment, they will stop reacting to them once they get used to them.
Science of Dogs Seeing Glass
Dogs will react differently to glass depending on their previous experience with it. It's most connected with what they are used to. For instance, if you have a glass door that leads to the backyard, and that door is mostly closed, your dog will be reluctant to go through it even when there is no glass there.
This isn't because your dog can't really see the glass, but it’s because of their habit. They are used to knowing there's a barrier there, and if, say, the door is closed but the glass has been removed, they will not try to go through it and will eagerly wait for you to open the door.
When it comes to mirrors, the dog will react to their reflection, but they are not aware that it's their reflection. When they first encounter it, they will see the reflection as another dog and they either have a playful or a stiff response. They will also quickly catch on that no matter what their response, they are not getting any other response than that of their own.
Soon thereafter, they will stop responding to their reflection altogether. This is a mechanism called habituation, where your dog stops reacting to a stimulus that was causing a reaction before. This is not limited to mirrors. It can be anything in their environment, such as TV, trains, the phone ringing, and more.
Dogs can use mirrors as tools, for instance, to find objects or people quicker. This, however, depends on each individual dog, as studies show that some do indeed use mirrors to find objects quicker by spotting the reflection first, while others don't use this at all.
Training of Dogs to See Glass
Your young pup will probably react to mirrors for a while until they realize that their responses are never met with different one. As time goes by, they will become used to mirrors and seeing another dog there, but will not respond.
When it comes to glass, it all boils down to previous experience. Also, dogs will easily see glass if it's not clean—they will more easily discern there's a type of barrier there because of the dirt.
If you are rearranging your house, or moved to a new house, and own a brand-new glass door, your dog will need some time to get used to it. It's best to introduce this weird new barrier immediately, so you eliminate the risk of your dog bumping into it, or worse, running into it at full speed as they try to reach the yard.
Written by Charlotte Ratcliffe
Veterinary reviewed by:
Published: 06/12/2018, edited: 04/06/2020