Dogs notice when you are sad, happy or suspicious. They can even detect cancer. Turns out dogs know more about your emotions and health than you ever suspected.
You are a generous person (or not)
I make judgments about you based on your actions. Researchers at the University of Milan observed with dogs people who shared their food with a beggar and other people who told the beggar to leave. Later, when these people waved to the dogs at the same time, the dogs rushed to the generous people.
You don’t like someone
When you have negative feelings about someone, I can hear your breathing change, watch your body stiffen slightly, and even feel the subtle pheromones your body emits. So, if your in-laws suspect that I don’t like them, it may just be because you don’t really like them.
Humans are like sponges. You pull out volatile organic compounds from everything you touch or from where you’ve walked. If you just visited, say, the supermarket, I would smell the carrots and fish counters, the food you bought, and maybe even the people you were with at the checkout. I can smell something 100 million times more subtle than the faintest smell you can smell.
You can get cancer
Some of us learn to detect different types of cancer by smelling certain chemicals that cancer cells may emit. In some studies, we were 88% accurate at detecting breast cancer to 99% accurate at detecting lung cancer.
You’re going home
We’ve learned your schedule and know roughly when to expect you home each day. But even if you arrive home at an unusual time, I can detect the sound of your particular car on the street, and I’m always in listening mode to hear it.
You’ve had a fight with your partner
Even if you don’t speak in front of me, I will notice your jerky tone, the fact that you don’t speak, the stiffness of your posture or the fidgety way you walk or open drawers. Some of us get sick to our stomachs when our owners argue.
You need protection
Do I sleep next to your bed instead of my usual spot when your spouse is out of town? Do I stay closer to your leg than normal when we walk through a dark area? I can sense the adrenaline your body releases when you are afraid and I am also more alert when someone in the family is away.
You’re going on a trip
I hate it when you leave, so I’ve learned to take note of all the clues that announce an impending departure: suitcases pulled from the closet or the way you put your clothes on your bed. Some of us start shaking and yelping because we’re experiencing anxiety spikes. One study found that hearing classical music, when we are alone, can help us calm down.
You can’t resist our big eyes
Researchers have found that your body releases oxytocin (the same hormone that is released when you look at your baby) when we make eye contact with you. So there’s a reason we look at you with love when we want something: it works.
I can pick up almost imperceptible signals in your body language-the way you glance or pick up the leash-that tell me what you’re planning. In one study, dogs were able to easily identify the location of hidden food simply by following a human gaze.
You don’t feel well
We can be trained to sniff out everything from a drop in your blood sugar to a migraine. A growing number of epilepsy patients are getting dogs to alert them to a seizure before it happens. At a Hawaiian hospital, dogs sniffed out urinary tract infections in paralyzed patients who couldn’t report their symptoms.
Your baby is vulnerable
I know your little one is a member of our clan, and I also know he or she is the most vulnerable. Because I have a strong instinct to guard my family members, I can be extremely protective. That’s why I bark aggressively when someone approaches the stroller and why you should be alert if someone is playing with your child while I’m around.
I’m a master at reading your body language and emotional state. One study found that I can tell if someone is sad just by reading facial expressions (even if I’m only looking at a photo of half a face!). I am also more likely to approach someone who is crying than someone who is humming or talking, another indication of my high empathy.