Can Dogs Sense Health Problems in Humans?

Odd? Maybe. But it could be more than just a quirky habit.

Dogs have an incredible sense of smell. It's how they explore the world. But research suggests it might also help them pick up on changes inside our bodies, like illness.

Some dogs can detect shifts in our health through subtle changes in scent. We're talking about things like blood sugar, infections, or even early signs of cancer. All from odor cues we can't sense, but they can.

It’s a rare feat. But it’s real.

So before brushing it off as odd behavior, it might be worth paying attention. Because dogs may be sensing more than we think. Especially when it comes to humans and health.

Can Dogs Sense Health Issues?

It sounds like something out of a movie, doesn’t it?

A dog sniffing out a disease before a doctor even runs a test. But the idea isn’t as far-fetched as it seems.

Dogs have been trained for years to help patients with seizures or diabetes. They can alert someone before a seizure starts. Or respond when blood sugar levels crash. That’s not just luck. It’s training, instinct, and a nose that’s way more powerful than ours.

Some researchers are even exploring how dogs might help with screening for certain conditions. From cancer to migraine warnings. Even signs of stress that most humans would miss.

Of course, not every dog has this skill. And we’re still learning how it works. But the early results are hard to ignore.

Dogs may be picking up on subtle changes that happen in the body before a disease fully shows up.

How Are Dogs Able to Detect Health Problems?

Dogs have up to 300 million scent receptors packed into that snout. Humans? Around 6 million. So when it comes to detecting tiny shifts in the body, they’re in a different league.

Some studies suggest dogs can smell changes in our breath, skin, sweat, or even urine. That’s because illness may trigger something called volatile organic compounds or VOCs. These are chemical changes that happen when the body is under stress or fighting disease. Some dogs can detect that, even in early stages.

But it’s not just about sniffing.

Dogs are animals built on observation. They watch how we move. How we sit. Even how our breathing changes when we’re off. They pick up on body language long before we know something’s wrong.

A slight limp. A dropped routine. A different scent from a patch of skin.

Some dogs are trained to alert patients to these changes. Others just seem to know. Whether it’s detecting melanoma on the leg or staying close during a panic attack, their instincts kick in.

Of course, not every dog can do this. Breed, environment, and how closely they’re bonded with you all play a role.

6 Health Problems Dogs May Be Able to Detect

Not every dog is a medical genius. But some can sniff out more than leftover lunch.

From chronic illness to sudden health events, dogs have shown surprising skill in picking up signs of trouble. Some are trained. Others just seem to know when something isn’t right.

Let’s look at six health problems dogs might be able to detect and how.

1. Cancer

This is one of the most widely studied areas of canine detection.

Dogs have picked up on several forms of cancer by scent alone, including:

• Breast cancer
• Lung cancer
• Colorectal cancer
• Skin cancer
• Bladder cancer
• Prostate cancer
• Cervical cancer

In one study published in Gut, dogs detected colorectal cancer with over 90% accuracy using breath and stool samples. Another study in Integrative Cancer Therapies found that dogs could detect breast cancer from clothing worn by patients.

The theory? Tumors may produce specific compounds the body releases through breath, sweat, or urine. Dogs pick up on that scent.

They’re not replacing doctors. But they may be leading researchers toward new early screening tools.

2. Seizures

Dogs sensing seizures isn’t new. But it’s still a bit of a mystery.

Some dogs can detect subtle changes before a seizure hits. These changes might be in body odor, body temperature, or behavior. And they often respond by:

• Alerting the person
• Staying close
• Seeking help if trained

Even without formal training, some dogs naturally develop this ability. It’s especially common in people living with epilepsy, where dogs may offer both support and early warning.

Researchers don’t fully understand how it works. But those who live with seizure-alert dogs often say they know before they do.

3. Low Blood Sugar (Hypoglycemia)

For people with diabetes, sudden drops in blood sugar can be dangerous. Some dogs are trained to detect low blood sugar through changes in:

• Sweat scent
• Breath composition
• Behavior or movement

These dogs are often called diabetic alert dogs. But not all of them are professionally trained. Some pet dogs pick up on the signs naturally.

They may nudge, paw, or lick to get attention. And many people report that their dog responds before a glucose monitor does.

4. Infections

Certain infections give off a distinct scent.

Dogs have been trained to detect:

• Urinary tract infections
• Clostridium difficile (C. diff)
• COVID-19

In some studies, dogs have identified infected patients by sniffing urine or sweat samples.

During the pandemic, scent-detection dogs were used in airports and public spaces to help screen for COVID-19. The results weren’t perfect, but they were promising enough to continue the research.

Again, this likely comes down to chemical changes the body releases during infection.

5. Migraines

There isn’t a lot of lab research here, but there are plenty of personal stories. Some people say their dogs sense a migraine before it hits. They might paw at them, stay close, or act restless.

It’s not clear what they’re reacting to. But it could be small shifts in scent, posture, or energy that happen before symptoms show.

If you live with chronic migraines, you might notice a pattern too.

6. Stress, Anxiety, or Emotional Distress

Dogs are surprisingly tuned in to human emotion. They respond to fear, anxiety, or stress, even when we try to hide it. That’s why service dogs are often trained for mental health support, including:

• PTSD
• Panic disorders
• Chronic anxiety

They watch our body language, listen to changes in tone, and may even respond to stress-related scent markers.

FAQ on Dogs and Human Health Detection

• Can dogs smell cancer? Yes, some dogs can detect certain cancers by scent. They pick up on changes in the body’s chemistry, often through breath, urine, or skin.
• Can my dog do this, too? Maybe. Some dogs have a strong sense of smell and sharp instincts. But not all dogs are wired the same. Training, bond, and breed can all play a role.
• Why does my dog act strangely when I’m sick? Illness can change your body language, scent, and energy. Your dog may notice those shifts and respond in their own way.
• Do dogs know when I’m stressed or anxious? Often, yes. Dogs read cues like tone of voice, posture, and smell. Fear, anxiety, and stress can trigger subtle changes they may sense.
• How can I tell if my dog is sensing something wrong? Look for unusual behavior. Clinginess. Sniffing one spot on your body. Restlessness. Or staying close when they usually don’t. It doesn’t always mean something serious, but it’s worth noticing.
• Should I be concerned if my dog keeps sniffing one part of my body? Not always. Dogs explore with their noses. But if it becomes persistent and focused, especially near the skin, it may be worth getting checked by a doctor.
• Can medication affect how my dog reacts to me? Yes. Some medications can change your scent or behavior. Your dog might respond to that, especially if it’s new.
• Why are dogs so good at this? Dogs are highly social animals. They rely on their sense of smell and close observation to understand the world—and the humans in it.

Are Dogs the Health Detectives We Never Knew We Had?

It’s hard not to be impressed by what dogs can do. Their sense of smell outperforms any machine we’ve built so far. And yet, the way they pick up on disease still feels like a mystery.

Science is trying to keep up. Studies with patients have shown dogs detecting changes in odor linked to different illnesses. From cancer to infections, their noses may help researchers develop new ways to find problems earlier.

But it’s not just about the nose. Dogs also read our emotion and behavior. They notice small shifts in routine or body language that hint something’s off.

This doesn’t mean every odd look or sniff from your dog signals trouble. Sometimes it’s just a mood. Other times, it might be worth paying closer attention.