Shocking Things Dogs Can Smell That Humans Can’t

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It’s already widely known that smelling is part of a dog’s natural behavior — they use it to understand the environment around them and pick up information.

A typical dog’s nose contains up to 300 million olfactory receptors, or odor receptors. That’s a pretty large number, considering us humans only have 6 million. Depending on the breed, a dog’s sense of smell can be anywhere from 10,000 to 100,000 times better than ours. Plus, the part of their brains that analyze and process scents is about 40 times greater than ours.

That means that a dog’s nose can pick up scents that we simply can’t.

Sure, they can smell if you’ve been around another pup, but there are some other surprising — and frankly, impressive — things that dogs’ noses can pick up.

Coronavirus

This might be hard to believe, but it’s true: dogs can sniff out COVID-19. Researchers have long known that viruses have specific odors.

Based on previous work showing that dogs can detect humans with a malaria infection, researchers at the University of Pennsylvania are currently training eight Labrador Retrievers to detect COVID-19. It would provide a quick, non-invasive way to screen people in airports, hospitals, or other public spots.

Pregnancy

Dogs are so sensitive to smells that they can smell our hormones. Pregnancy, of course, changes the hormones in the body. Dogs can detect this change in our urine, but the change is also detectable in our body scents that dogs can smell.

Emotions

Similarly to the way dogs can detect pregnancy hormones, they can smell other hormonal changes, too. This includes those involved in our emotions. When we have changes in our emotions, we experience changes in stress hormones like cortisol or adrenaline, or happy hormones like oxytocin. Dogs can detect these changes, thanks to sweat or even our breath.

Cancer

Dogs have even been trained to use their highly evolved sense of smell to detect cancer in its early stages. A cancerous tumor produces proteins that dogs can smell in urine. They can sense several types of cancer, including breast cancer, lung cancer, bladder cancer, and prostate cancer.

Diabetes

Here’s another health issue that your dog can detect. Dogs can actually sniff out a change in blood glucose levels, just from a person’s breath. Some dogs have even been specially trained to assist people with severe diabetes to warn them when their glucose levels have dropped too low.

Bed Bugs

It might sound gross, but dogs can sniff out the odor that bed bugs produce from their scent glands. The smell is only noticeable to humans in really large quantities, like in the case of a severe infestation. However, dogs can sniff it out before it ever becomes a problem, helping you rid your home of bed bugs before the infestation gets out of control.

Severe Weather

If your dog normally starts acting strange before a big storm hits, it’s because they can literally smell it coming. They can smell even the slightest changes in the air. This means that dogs can alert you to an approaching storm, like a hurricane.

Heat

New research shows that dogs actually have sensory cells at the end of their noses that act kind of like infrared sensors. They use them to detect very small changes in temperature, alerting them to when other dogs, people, or predators are nearby.