Hepper is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

Can Dogs Smell Sickness in Humans? What the Science Says

Nicole Cosgrove Profile Picture

By Nicole Cosgrove

jack russell dog leaning on its owner's lap

Dogs are known for their exceptional sense of smell. It is not surprising that they are used in many areas, including search and rescue, detection of illegal substances, and even medical diagnoses. But can dogs smell sickness in humans?

It is a question that has been asked for years, and in recent times, many studies have been conducted to investigate this claim. Given the studies available, we can say YES, dogs can detect various diseases in humans through smell. However, this still requires further research and evidence before dogs can be properly used in clinical practice.

In this article, we will explore the science behind the claim that dogs can detect human sickness through their sense of smell.

divider 10

Dogs and Their Sensitive Sense of Smell

Dogs have a highly developed sense of smell that is far more sensitive than humans. They have over 300 million olfactory receptors in their nose, while humans only have about 6 million. This means that dogs are capable of detecting even the slightest of odors that humans are unable to sense.

When a dog inhales, the air is split into two parts – one part goes to their lungs for breathing, while the other part goes to their olfactory system for scent detection. The scent detection part consists of a complex network of nerves, receptors, and brain areas that work together to process the smell.

golden retriever close up
Image Credit: JacLou DL, Pixabay

What Are Dogs Capable of Smelling?

Dogs have a remarkable ability to distinguish between different smells. They can pick up on subtle differences in scent, making them useful in various fields, such as detecting explosives, narcotics, and missing persons.

Now, dogs’ ability to detect scents are being explored for their potential application in healthcare. Given their incredible sense, dogs should be capable of detecting chemical changes in the body that humans cannot. These chemical changes may be indicative of certain medical conditions, such as diabetes, seizures, and even cancer.

Can Dogs Smell Sickness in Humans?

It is a well-known fact that dogs can detect certain medical conditions in humans. For instance, trained dogs can alert their owners of an impending seizure by detecting changes in the body’s odor. Moreover, some dogs are trained to sniff out cancer by detecting the volatile organic compounds (VOCs) that cancer cells emit.

The question remains – can dogs smell sickness in humans, such as the flu or a cold? There is no conclusive evidence to suggest that dogs can detect the flu or a cold in humans. However, some studies suggest that dogs can detect certain chemical changes in the body that are associated with sickness.

dog staring its male owner
Image Credit: StockSnap, Pixabay

Studies That Suggest Dogs Can Smell Diseases in Humans


In 2006, a study was published showing that dogs are able to detect cancer from the presented breath samples. This study was later supported by another study in 2019 that showed that dogs can also detect cancer from blood samples with up to 97% accuracy as well!

Parasites (Malaria)

Another study in 2019 found that dogs can detect the odor of sweat from people with malaria. The researchers trained dogs to detect the odor of socks worn by malaria-infected individuals. The dogs were able to distinguish between the socks of infected individuals and those of healthy individuals with an accuracy rate of 70%.


A more recent study conducted in 2020 found that dogs can detect COVID-19 in humans with an accuracy rate of up to 94%. The study involved training dogs to distinguish between the odor of sweat samples from COVID-19 patients and healthy individuals. The dogs were able to detect COVID-19 with high accuracy, even in asymptomatic individuals.

maltese dog sitting on the floor and looking up
Image by: Pezibear, Pixabay


A study published in 1998 in the journal Epilepsy Research investigated whether dogs could detect the odor of sweat from people with epilepsy and distinguish it from the sweat odor of people who had not had a seizure. The researchers collected sweat samples from patients during seizures and during non-seizure periods and presented them to trained dogs to see if they could distinguish between the two. The dogs were able to accurately identify the seizure odor with a success rate of 97%. This study provides evidence that dogs can detect changes in the odor of people with epilepsy during seizures and suggests that their exceptional sense of smell may be used as a tool to alert individuals to an impending seizure.


There is also evidence that suggests dogs can detect diabetes through scent detection. A study published in Diabetes Care in 2013 investigated whether trained dogs could accurately identify the scent of hypoglycemia, or low blood sugar, in people with type 1 diabetes.

The study found that trained dogs could accurately detect hypoglycemia by scent alone and that their alerts were more reliable than current glucose-monitoring technologies. The study suggests that trained dogs could be used as an alternative or complementary tool for detecting hypoglycemia in people with type 1 diabetes.

The science behind the detection of sickness in humans by dogs is still in its early stages. While these studies suggest that dogs can detect certain chemical changes associated with sickness, more research is needed to confirm these findings.

dog smelling human hand
Image by: Marco Malz, Shutterstock

How Can Dogs Help in Detecting Various Sickness?

Despite the lack of conclusive evidence, dogs can still play a vital role in detecting sickness in humans. Trained dogs can be used to detect various medical conditions, such as diabetes, seizures, and cancer. They can also be used in medical facilities to screen patients for infectious diseases, such as COVID-19.

In addition, dogs can help individuals with certain medical conditions by alerting them to an impending medical emergency. For example, dogs can be trained to alert their owners to an oncoming seizure or a drop in blood sugar levels. These alerts can give the owner time to take preventive measures or seek medical attention.

Divider 2

Final Thoughts

The evidence suggests that dogs can smell sickness in humans, but more research is needed to fully understand the scope of their abilities. Nevertheless, their unique sense of smell makes them valuable assets in various fields, including medicine. As our understanding of dogs’ olfactory capabilities continues to grow, it is possible that our furry friends will become even more integral to our healthcare systems in the future!

Featured Image Credit: Javier Brosch, Shutterstock

Related Articles

Further Reading

Vet Articles

Latest Vet Answers

The latest veterinarians' answers to questions from our database