Can cats smell cancer in humans? There are anecdotal reports of cats behaving differently around people who were later diagnosed with cancer, but there is currently not enough scientific evidence to say that cats can reliably detect or diagnose cancer by smell.
Cats have a highly developed sense of smell that they use to understand their environment, communicate and interact with other animals. This raises an interesting question: could cats also detect changes in the human body associated with disease?
Here’s what we know about cats, their sense of smell and cancer detection.
Can Cats Detect Cancer?
There are stories from cat owners who believe their pets noticed something unusual before they were diagnosed with cancer.
In some reports, cats repeatedly focused on or touched a particular area of their owner’s body. The person later discovered that the same area was affected by cancer.
These stories are interesting, but they are anecdotal evidence, not scientific proof that cats can smell cancer.
A cat may react to changes in a person’s scent, behavior, routine, temperature or other characteristics without specifically detecting a cancerous tumor. Without controlled research, it is impossible to determine exactly what caused the behavior.
There is therefore an important distinction between saying that a cat behaved differently around a person with cancer and saying that the cat detected cancer.
How Strong Is a Cat’s Sense of Smell?
Cats rely heavily on their sense of smell to understand the world around them.
Their olfactory system helps them identify other animals, investigate unfamiliar objects, recognize familiar scents and gather information about their surroundings.
Cats also have a specialized organ called the vomeronasal organ, or Jacobson’s organ, which is involved in detecting certain chemical signals.
Research has shown that olfaction is an important part of feline sensory perception.
Read the Merck Veterinary Manual’s overview of feline behavior and communication
Because cats rely so heavily on smell, researchers have investigated their ability to discriminate between different odors.
A 2017 review published in Applied Animal Behaviour Science discussed the potential for cats to use their olfactory abilities in tasks involving odor discrimination. The researchers noted that cats’ olfactory abilities could potentially be applied to areas such as medical scent detection, although this potential should not be confused with evidence that cats currently diagnose diseases.
Read the 2017 research paper on feline olfactory discrimination
Can Cats Smell Human Diseases?
The possibility that animals can detect human diseases through smell has attracted considerable scientific interest.
Researchers have investigated medical scent detection in several animal species, particularly dogs. Some studies have explored whether trained animals can distinguish biological samples associated with certain diseases.
Cancer can cause biochemical changes in the body. Some of these changes can produce volatile organic compounds, or VOCs, which may be detectable through smell.
However, detecting disease-related compounds in controlled laboratory samples is different from an animal diagnosing cancer in a person in everyday life.
For cats specifically, there is not enough evidence to establish that they can reliably detect cancer or other human diseases.
Learn more about cancer research and diagnosis from the National Cancer Institute
Why Are There Stories of Cats Detecting Cancer?
Anecdotal reports can be compelling, but they cannot establish whether a cat actually detected cancer.
There are several possible explanations for unusual behavior around a person who has an illness.
For example, a cat could respond to:
- Changes in a person’s body odor
- Changes in medication or diet
- Changes in body temperature
- Changes in behavior or routine
- Changes in movement
- Increased attention or interaction from the person
- A scent associated with another health or environmental change
It is also possible for an unusual interaction to receive more attention after a person receives a diagnosis. This can make a previous behavior seem more significant in retrospect.
That does not mean the stories are necessarily false. It simply means that an anecdote cannot tell us what caused the cat’s behavior.
Controlled research would be needed to determine whether cats can identify cancer-related odors and whether they can do so reliably.
Could Cats Be Trained to Detect Cancer?
Cats can learn behaviors through training, despite the common perception that they are difficult to train.
Their ability to learn does not necessarily mean that they can be trained to detect cancer, however.
For a reliable medical detection system, researchers would need to establish that cats can consistently distinguish cancer-associated samples from non-cancer samples under controlled conditions.
They would also need to determine how accurate the cats are, whether they can distinguish between different types of cancer, and whether their performance can be reproduced across different animals and testing environments.
At present, there is not enough evidence to answer those questions for cats.
Can You Tell If You Have Cancer Because Your Cat Acts Differently?
No.
A cat behaving unusually around you should not be considered a sign that you have cancer.
Cats can respond to many changes in their environment and to changes in the people they live with. An unusual behavior may have nothing to do with illness.
If you have symptoms that concern you, speak with a healthcare professional rather than relying on your cat’s behavior as a form of cancer screening.
Likewise, routine cancer screening should follow the recommendations appropriate for your age, risk factors and medical history.
So, Can Cats Smell Cancer?
Can cats smell cancer? The honest answer is that we do not currently know.
Cats have sophisticated olfactory abilities and can distinguish between different smells. There is also scientific interest in whether animals can identify disease-associated odors.
However, anecdotal reports about cats reacting to people with cancer are not enough to establish that cats can detect cancer. More controlled research would be necessary to determine whether cats can reliably identify cancer-related odors and whether that ability could have a practical medical application.
For now, your cat’s unusual behavior can be interesting to observe, but it should not be used as a substitute for medical testing or professional healthcare.
As research into animal scent detection continues, scientists may learn more about what cats can detect through their remarkable sense of smell.
