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Dogs can smell far more than we ever could imagine. Their noses are not just for sniffing around—they allow dogs to detect invisible signals in their environment that humans cannot sense at all. From illness in a loved one to dangerous substances hidden from view, dogs can smell things that would leave us completely unaware.
Why Dogs’ Noses are So Powerful
Before we jump into the ten, a quick look at what makes dogs smell so sharply:
- Dogs have up to 300 million olfactory receptors, compared to about 5-6 million in humans.
- Their brain areas devoted to smell are much larger in proportion.
- They also have a vomeronasal organ (Jacobson’s organ) that detects pheromones and subtle chemical signals.
With that foundation, here are 10 things dogs can smell that humans absolutely cannot (or not under normal circumstances).
10 Things Dogs Can Smell That Humans Can’t
1. Pregnancy Changes & Hormonal Shifts
There is evidence that dogs can smell the hormonal changes in pregnant people, or even in women about to ovulate, because of changes in pheromones and scent.
2. Approaching Seizures or Epileptic Episodes
Some dogs are trained or seem naturally able to sense biochemical changes that precede seizures, sometimes minutes or more in advance. Their noses detect changes in body chemistry that humans simply cannot.
3. Emotional States Like Fear, Anxiety, or Mood Shifts
Humans release hormones, pheromones, and sweat compounds when emotional states change. Dogs pick up on subtle odors associated with fear, stress, anger, or happiness. That’s part of why your dog might cuddle when you’re sad or back away when you’re angry.
4. Disease (Cancer, Diabetes, and More)
Dogs can smell volatile organic compounds (VOCs) emitted from the body when someone has certain illnesses. Studies show dogs can smell cancer (e.g., lung, breast, skin) with high accuracy, sometimes even before it’s clinically obvious. They can also detect low blood sugar in diabetics.
5. Infectious Diseases (Including COVID-19)
Research has shown that dogs can detect some diseases like COVID-19 by sniffing sweat or breath samples. Their olfactory system can pick up chemical markers of infection before standard symptoms appear.
6. Bedbugs, Pests, and Hidden Infestations
Detection dogs are frequently used to find bed bugs, which emit minute chemical signals. Dogs can detect infestations that are hidden in mattresses or wall voids long before humans notice the signs.
7. Changes in Blood Sugar (Hypoglycemia & Hyperglycemia)
Even without specialized training, many diabetic-alert dogs can notice when blood sugar levels in their owner are dropping. The chemical shifts in breath or sweat are imperceptible to us, but very real to them. Learn more here.
8. Human Remains / Decomposing Tissue
Cadaver dogs are trained to detect human remains (or parts/tissue) even when buried, underwater, or decomposed. Dogs can smell chemicals given off in decomposition that humans cannot smell until later (if at all).
9. Where Someone Has Been & What They Ate
Dogs don’t just smell a person—they smell their history. Where they’ve been, what they ate, who else they’ve met. All those odor particles cling to clothes, hair, sweat, etc. Dogs can “read” a lot from scent trails. Humans have a much weaker ability to track scent trails or identify smell histories.
10. Trace Substances: Narcotics, Explosives, Drugs, Contraband & Accelerants
Trained detection dogs are used by law enforcement to detect drugs, explosives, contraband electronics, and the scent of accelerants (used in arson). Humans simply cannot detect such materials by smell, particularly when they are masked or in trace amounts. Learn more here.
What This Means for Your Dog’s Care
Dogs’ sniffing superpowers are amazing, and knowing these can help you better care for your dog—and appreciate them more. Here’s how:
- Regular grooming, ears & teeth care: Because dogs use their nose so much (sniffing everywhere), keeping fur, ears, and mouth clean helps avoid infections that might alter scent or cause discomfort. (At Dog House Dubai we offer professional ear cleaning, teeth brushing, and grooming to keep your dog fresh and healthy.)
- Mental stimulation via smell games: Give your dog safe scents to explore. You can hide treats, toys, or safe scent items to engage their nose.
- Monitoring health via behaviour changes: If your dog seems suddenly disturbed by smells humans don’t notice, or sniffs intensely at something invisible to you, it could be a sign of illness or pain.
- Safe product choice: Because dogs’ noses are so sensitive, using hypoallergenic shampoos or gentle perfumes (which we provide in our Shower & Blow Dry + pet-friendly perfume sessions at Dog House Dubai) helps prevent irritation.
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Conclusion
Dogs’ noses are nothing short of extraordinary. From detecting illnesses to sensing emotions, their world is shaped by scents we can’t even imagine. This superpower doesn’t just make them fascinating—it also makes them lifesaving companions in fields like medical detection, search and rescue, and security.
For everyday pet owners, it’s important to remember that your dog’s sense of smell is constantly at work. Every walk, car ride, or visit to a new environment is a rich sensory experience for them. Giving your dog opportunities to sniff and explore is one of the simplest ways to keep them mentally stimulated and happy.