Can Dogs Smell Fear? The Science Behind How Dogs Sense Emotions

Those noses really can sniff out how we are feeling.

It’s one of these weird old sayings that “dogs can smell fear” and it turns out to be true. Our dogs have truly exceptional senses of smell, far more powerful than ours. So much so that they are also able to sniff out human emotions like fear, stress and even happiness. 

And here’s the surprising part: a dog’s ability to smell our fear can actually affect their own emotional state too.

How do dogs smell fear?

Dogs have an olfactory system that’s 40 times more powerful than ours. While humans have about five million scent receptors in their noses, dogs have an amazing 220 million. This gives them the ability to detect scents at concentrations nearly 100 million times lower than what humans can perceive.

When humans experience fear, the body releases stress hormones like adrenaline and cortisol. These changes cause subtle shifts in body odour and increase sweat production, releasing chemicals known as chemosignals. Dogs are highly sensitive to these and they can pick up on the slightest changes in a person’s scent.

A study at the University of Naples found that dogs exposed to the scent of a fearful human showed signs of stress themselves. Their heart rates increased and they displayed behaviours like lip-licking, looking away and seeking reassurance from their owners. This suggests that dogs not only smell fear but that it also impacts their own emotions. Essentially, when you’re nervous, your dog might feel anxious too.

Can dogs smell other emotions too?

It’s not just fear that dogs can smell. Thanks to their ability to detect chemosignals, dogs can sense a range of emotions from humans:

• Stress – When we’re stressed, our bodies produce cortisol, a hormone that affects our sweat and breath. Dogs can pick up on these changes and may react by seeking reassurance, pacing or staying close by.
• Happiness – The scent of happiness is different from stress or fear. When dogs are exposed to the sweat of a happy person, they tend to become calmer and more relaxed. They may even seek out social interaction, reflecting the positive energy they detect.
• Anxiety – Anxiety is closely linked to fear, and like fear, it triggers the release of certain hormones. Dogs can pick up on these changes and may react by becoming more alert or protective.
• Sadness – Dogs seem to have an intuitive understanding of sadness, often approaching and comforting their owners when they’re upset. While this could be due to visual cues like facial expressions, the chemical signals released when we cry may also play a role.

Dogs have evolved alongside humans for thousands of years, and their ability to detect and respond to human emotions has probably played a part in their domestication. Being able to sense fear, stress, and happiness would have helped early dogs form stronger bonds with humans, ensuring they received protection, food and companionship in return.

How does your dog react to your fear?

When a dog senses that we are afraid they react. Depending on the dog’s temperament, breed and training, their response can vary. Some dogs become anxious themselves, pacing or licking their lips as a sign of stress. Others may become more protective, placing themselves between you and the source of fear. Guard dogs have been trained to respond to perceived threats, so if they smell your fear, they may interpret it as a cue to become more vigilant.

In the wild, fear is contagious. When one member of a pack senses danger, they alert the others, causing a ripple effect of heightened awareness. Modern dogs still retain this instinct. If you’re visibly scared and your body releases fear-related chemosignals, your dog may think something is wrong and react accordingly.

How can you support your dog’s emotional well-being?

If dogs can smell our fear and other emotions, it’s important to think about how our own emotional state affects them. If you’re feeling anxious, stressed or upset, your dog may sense it and become unsettled too. But don’t worry, there are ways to support your dog’s emotional well-being, even when you’re feeling stressed.

1. Stay calm and reassuring – If you’re feeling anxious, try not to transfer that energy to your dog. They pick up on subtle body language cues as well as chemosignals. If you remain calm and composed, your dog is more likely to do the same.
2. Use positive reinforcement – Dogs respond well to positive reinforcement. If your dog is feeling anxious because they’ve picked up on your stress, engage them with activities they enjoy, like a game of fetch or puzzle toys.
3. Create a safe space – If you know you’re going to experience something stressful (like watching a scary movie or dealing with a thunderstorm), provide your dog with a calm, safe space where they can retreat if they start to feel uneasy.
4. Consider training or desensitisation – If your dog tends to react strongly to your fear or anxiety, training them to stay calm under pressure can help. Desensitisation training can teach them to remain relaxed, even in high-stress situations.
5. Prioritise your emotional well-being – Taking care of your own mental health isn’t just good for you, it’s good for your dog too. If you feel calm and relaxed, your dog is more likely to feel that way too.

So, the next time you’re feeling anxious or upset, remember that your dog is likely picking up on those feelings. But with a little care and patience, you can support both your emotional well-being and your dog’s. 

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