5 min read


Can Dogs Smell Illness?



5 min read


Can Dogs Smell Illness?


Dogs are known for their sense of smell. All dogs, regardless of their breed, have a better sense of smell than humans, and some breeds are better at smelling things than others. It's why they're used as drug-sniffing dogs for the police, trackers for detectives, and hunters for, well, hunters. But you may be surprised to learn that our doggo's capability can extend even farther beyond these different uses, all the way into the medical field!

No, we're not talking about dogs becoming doctors. No matter how smart you think your doggo is, there's no way that they're going to be able to operate on a tumor or perform open heart surgery. But because dogs' senses of smell are so powerful, they actually are able to sniff out certain illnesses in humans, which can be vital to saving a life or treating a disease. Studies have shown that as we become sicker, our body chemistry changes in a way that dogs can specifically sniff out and alert us to. Depending on the disease, dogs are able to alert doctors to illnesses before they really begin to affect our bodies, which can be extremely important during the early stages of life-threatening illnesses, so we can get them treated as quickly as possible. 

So, it turns out that dogs really are man's best friend, not only because they provide a shoulder to cry on, entertainment when we're bored, and exercise when we need it, but also since they can actually save our lives!


Signs Your Dog Can Smell an Illness

Doggos the world over are starting to be trained to specifically smell out a disease or illness in a person. There are now woofers out there that are literally "cancer-sniffing dogs", who go around hospitals and other places and sniff out specific scents that are associated with cancer and other diseases. 

They're trained to react in a specific way with their handler to alert them that the person they're smelling is sick, or at least has the chance to become that way. That doesn't mean, however, that your untrained pooch can't sniff out or sense when you're sick! They may just let you know in a different way. 

Regardless of whether or not they're trained to do so, woofers can smell certain things that we can't, and some of those things are related to illnesses. For example, they can smell volatile organic compounds, which are associated with cancer, drops in blood sugar, which happens during a diabetic episode, or the hormones that are released when certain things are about to happen, such as a seizure or a migraine. 

And while we all wish our pooches could talk, we, unfortunately, haven't figured out a way for them to do so yet. As a result, they're going to let us know about these body changes (many of which we aren't even aware of!) in their own way.

Many owners have reported their dogs paying more attention to certain parts of their body before they knew that there was something wrong with it. For example, they may sniff certain body parts more than often, or lick them more than others. You may have a bunch of moles on your body, but your dog will ignore them and sniff or lick only one. Basically, you should probably get something checked out if your dog is paying attention to it in a way that you aren't used to or seems unusual. 

Additionally, other owners report hearing crying or whining when their dog knows they are sick. This not only has to do with their sense of smell but also the way we act when we're not feeling well. Dogs have been around us for thousands of years, and have picked up on our behavior changes when we're upset. As a result, they may also act like they're sad or may snuggle up to you in comfort. They may also act anxious since they're probably confused as to why we're not paying attention to what they're trying to tell us! 

Basically, if your pup is different than normal, seems to be crying randomly while looking at you and seems really snuggly, or incesesently licks a certain part of your body, you may want to schedule an appointment with your doctor to get it checked out. It may just be that your dog is trying to make sure you stay happy and healthy, the same way we do with them!

Body Language

If your dog smells an illness, watch for:

  • Staring
  • Alert
  • Barking
  • Whining
  • Sniffing
  • Whimpering
  • Licking

Other Signs

<p>More signs that your dog is trying to tell you that you are sick include:</p>

  • Excessive Licking
  • Staring Or Sniffing One Part Of Your Body
  • Random Whimpering Or Crying
  • Acting Clingy
  • Generalized Anxious Behavior
  • Acting Different Than Normal

The History Behind Dogs Smelling Illnesses in Humans


In regards to their sense of smell, dogs evolved from wolves over 10,000 years ago. However, they still retain many wolf-life traits and abilities. One of these traits is their superior sense of smell. Back in the day when wolves and doggos had to hunt for their food, it wasn't exactly easy for them to track down their dinner. 

As a result, their sense of hearing and their sense of smell evolved to become super strong, so that they could sniff out their prey when they were still or being very quiet. 

Because we've known for a while that dogs can smell illnesses in humans, they've been used as medical service animals for a long while. For example, many dogs that are service animals can smell their humans drop in blood pressure or the release of seizure-inducing chemicals before their owner feints or before a seizure occurs. 

These types of service animals have been trained to alert their owners as many as a couple hours beforehand that they're about to have a seizure or need to take their blood pressure medication, so their owner is at least prepared for it to occur, or can do something to prevent an episode from happening. 

The Science Behind a Dog's Sense of Smell


While we all know that dogs have a better sense of smell than we do, you may be surprised to learn their sense of smell is upwards of 50 times better than ours! "While human noses have 6 million receptor sites, a dog's nose can have up to 200 to 300 million." That's why they can smell so much better than we can, and are able to pick up things like chemistry changes that our nose just can't. 

Tons of studies have been done regarding our dog's abilities to sniff out diseases in humans. "In a 2006 study, five dogs were trained to detect cancer based on breath samples. Once trained, the dogs were able to detect breast cancer with 8 percent accuracy and lung cancer with 99 percent accuracy", and this was across all four stages of the diseases. Sometimes, they even did a better job than human medical tests! 

Owners have also reported to scientists in the past that their pooch acted differently around them for a reason that the owner couldn't figure out. They reported crying, as well as sniffing or licking a certain area more than normal. When the owners got these areas checked out, many of them were cancerous, or had other things wrong with them! The more studies that are done, the more we find out the true capabilities of our woofer's nose, and their ability to safe lives. 

Training Your Dog to Smell Disease


There are a lot of programs out there that train dogs to be service animals, some specifically highlighting being able to sniff out diseases and illnesses, and others training a pooch to help their owner with an already-diagnosed disease. If you're interested in getting your doggo into one of these programs, or perhaps getting a pooch that can help you with a chronic illness, it's helpful to check these programs out.

As for training a "lay" dog who isn't specifically trained to sniff out illnesses, it's actually more about training you than training your pooch! It's important to note as owners how our dogs act normally, so we will notice quickly when they're acting differently. Since our dogs can't talk to us, they're going to let us know that we're sick through their body language and behavior, so we need to know how they act when they're uncomfortable. 

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Written by Katherine McCormick

Veterinary reviewed by:

Published: 04/27/2018, edited: 04/06/2020

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