Dogs are best known for their sense of smell and hearing. Service dogs, for instance, are specially trained to help humans in disaster areas, as well as in police, military, and fire work. Their keen senses are vastly superior to ours in many ways, and truly show they are our best friends when they put those senses to use for us.
With an extraordinary sense of smell, dogs certainly excel, but what about their vision. Is it also superior? Most of us are aware that a cat’s vision is much better at night, but what about a dog's? We know dogs can hear some spectrums that we cannot, but can they also see certain parts of the spectrum that are beyond our abilities? For example, what about infrared?
The truth is that dogs are not able to "see" infrared, but they may be able to sense it in another way.
Signs Dogs Can Sense Infrared
Whenever your canine friend sees or senses something that is of interest to them, they will react. Their body language will tell you straight away that something has caught their attention. They may react in a friendly, curious manner, or maybe even aggressively should they feel threatened in any way.
Even though your dog may not be directly seeing something in the infrared light spectrum, they may be sensing a thermal heat nearby and may exhibit signs of:
Alertness – once your dog senses a heat source, they will instantly become alert while they assess whether it’s a threat or not.
Whining – your dog might whine at the object or phenomenon because they really want to get closer to it, or they really want to get away from it.
Barking – should your dog feel threatened or scared, they will start barking.
Cowering – should your dog be forced to interact and still be scared, they might cower and try to make themselves smaller.
Growling – should your dog not be able to get away from a perceived threat, they may also start growling and showing signs of aggression.
Raised ears – in the majority of cases, however, an aggressive stance will not be your dog’s natural response; they will often just be curious, which you can tell by their raised ears.
Sniffing – in order to assess whether the object they are curious about is edible, they will sniff it.
Tail wagging – when your dog decides whether the subject of their attention isn’t a threat, they will most often start wagging their tail.
History of Dogs Sensing Infrared
Even though your dog’s senses of smell and hearing are keen and very sensitive, their sight is actually inferior to ours. Like their wolf ancestors, dogs have fewer rods and cones in their eyes than we do, which has caused scientists to speculate that they only see 2 out of 3 colors, most likely blue and yellow.
Wolves instead evolved specialized sight to hunt in low light conditions that allowed them to perceive movements more easily. Unlike some other predators, however, wolves and dogs didn't evolve the ability to see infrared light. Instead, they possess a secret sense that allows them to sense thermal heat located at the tip of their nose.
Science Behind Dogs and Infrared
The specialization that allowed the dog’s ancestors to excel at low light conditions, such as dusk and dawn, is also the very reason that your dog can’t see infrared.
The anatomy of a dog’s eyes tells us what they do see. In the retina, there are rods and cones that perceive the light filtering into the eye. The cones are specialized to provide vision when there’s a lot of light, while the rods help with seeing in low light conditions. Both humans and dogs have these, but dogs have many more rods in their eyes, allowing them to see much better in lower light conditions.
While humans have what is called trichromatic vision, our dogs have dichromatic; that is, they see only a part of the spectrum that we can see, namely the blues and yellows. But new evidence is mounting that they may be able to see ultraviolet light, an adaptation that may have helped them distinguish light-colored animals against a light background such as snow.
Nature, however, was sure to give dogs another way to sense nearby prey. A study involving Swedish and Hungarian scientists has discovered that the coldest place on a dog can sense infrared or thermal heat. Right at the tip of that wet nose are a bunch of nerve endings that send signals to the brain when they sense a heat source. Wolves and dogs can use this additional sense to hunt when the conditions don't allow them to see or hear prey, much like snakes and bats do.
Training Dogs to Sense Infrared
Your dog has come equipped with the nerves and perception to sense infrared through their nose, but as a domesticated animal with little need for hunting prey, they may have relied on their other senses more often.
A dog can certainly be trained to more accurately use the sensitive skin on their nose to sense thermal heat, as the researchers who published their findings on this additional dog sense proved. Mostly, training will re-attune dogs to their additional sense, and teach them to recognize the signals sent from it. However, since this discovery is rather new, research in both the sense itself and training a dog to use it is ongoing.
By Charlotte Ratcliffe
Published: 05/31/2018, edited: 01/14/2021