According to Nan Talleno, a reporter for CBS Philly, both dogs and cats can detect illness in both humans and other animals.
They do so at least partly by scent, for both animals have a much better sense of smell than do humans.
A dog’s sense of smell is particularly impressive; depending on breed, a dog can have anywhere from 125 to 300 million scent receptors.
Humans have a paltry five million. It’s been speculated that wolves, the ancestors of dogs, use their ability to tell when a packmate is under the weather.
How good is a cat’s sense of smell?
Surprisingly good. According to JaneA Kelley, who writes for Catster, a cat’s nasal cavity contains around 200 million scent receptors – which means their sense of smell at least matches that of some dogs.
A cat can use her nose to locate prey, determine if something is poisonous, and find her way back home if she gets lost.
Predicting epileptic seizures
James Tozer, a writer for the “Daily Mail,” tells the story of Lily, a cat who serves her owner as a living medical alert system.
Nathan Cooper and his family got Lily in 2010, while she was still a kitten. Nathan has epilepsy and has roughly one seizure every week.
When she senses an impending seizure, the normally quiet Lily will alert the household by bounding up and down the stairs loudly meowing.
The family can then take steps to make certain Nathan doesn’t fall or otherwise hurt himself during the seizure.
On one occasion, Nathan stopped breathing after a particularly severe seizure. Lily saved his life by licking his mouth, which somehow caused him to start breathing again.
Lily’s ability to predict epileptic seizures is better-known and possibly more common in dogs.
In a 2004 article for the “National Geographic,” Maryann Mott described seizure alert dogs that can warn patients with epilepsy of impending seizures minutes to hours before they occur.
Such warnings allow the patient to either take an anti-convulsant, call for help, or get somewhere safe.
Seizure alert dogs are born with their ability to detect impending seizures. The Canine Seizure Alert Society of North Carolina, which has existed since 1996, identifies and trains dogs.
They can only work with dogs that already show some ability to detect imminent seizures, for that particular ability is one that can’t be taught.
On the other hand, they encourage “alerting behavior” like barking, pawing, or whining to warn the owner.
The Society will also train dogs to further assist people by pressing a button on the phone that dials 911 or by sitting with their owner.
The kitten who diagnosed breast cancer
In 2012, a staff writer for the “Daily Mail” reported a story about a woman who claimed that her ten-month-old kitten had detected her breast cancer.
Wendy Humphreys, who was 52 at the time, had a black-and-white kitten named Fidge. The kitten suddenly developed the odd habit of jumping up and sitting on Wendy’s right breast while she lay watching television.
After two weeks of this, Wendy decided to go to the doctor for her breast was sore, and she thought it was bruised.
The doctor spotted a lump and arranged for Wendy to undergo a scan that revealed the lump was cancerous. She had to have the breast removed and undergo chemotherapy.
Again, dogs are better known for their ability to sniff out cancer than are cats. In 2011, German scientists found that dogs could detect lung cancer in patients simply by smelling their breath.
The researchers hypothesized that cancer causes the body to produce volatile chemicals that cause the patient to develop a subtle and characteristic odor.
Daphne Sashin, a writer for WebMD’s “Healthy Pets” section, says that different studies have found that dogs can detect some types of cancer by smelling either the patient’s breath, urine sample, or stool sample.
Dogs can be trained to detect such odors and thus spot developing cancer even before a doctor can. Wendy believes that Fidge has similar abilities.
The cat who can predict death
Angela Lutz, a writer for Catster, tells the story of Oscar, an aging tabby-and-white cat who lives at the Steere House Nursing & Rehabilitation Center in Providence, Rhode Island.
While he is normally not particularly friendly, Oscar will sit with patients who are dying. Oscar is so adept at telling when someone is about to die that the staff makes a note of it when he visits a patient.
In fact, they will notify a patient’s family when Oscar visits them, for the patient will usually die within two to four hours.
As of 2015, Oscar has accurately predicted over 100 deaths. It is believed that Oscar is probably responding to the smell of a body shutting down.
Dr. David Dosa, a physician, and researcher at the nursing home, who also teaches at Brown University, has been fascinated by Oscar and his novel ability.
He wrote an essay about him for the “New England Journal of Medicine” in 2007 and wrote the best-selling book “Making Rounds With Oscar: The Extraordinary Gifts of an Ordinary Cat” in 2010.
WPRI posted the following video about Oscar:
Cats can also detect mood
According to Robin Wylie, a writer for BBC Earth, cats can read human emotions. In 2016, the science journal “Animal Cognition” described a study in which researchers from Michigan’s Oakland University worked with twelve cats and their owners.
They observed that the cats acted differently around an owner who was smiling rather than frowning.
If a cat’s owner was smiling, the cat would stay close to their owner and engage in such positive behaviors as purring or sitting in their owner’s lap.
The researchers also found that the cats always displayed friendly behavior to people they did not know, regardless of their mood.
The scientists speculated that while cats could read their owners’ facial expressions it took them time to do so.
Dogs appear to be better at reading human emotions than are cats – but they have a large advantage.
Humans domesticated dogs over 30,000 years ago, and they didn’t domesticate cats until around 10,000 years ago.
How do animals detect illness?
In the vast majority of cases, cats and dogs can detect illness by smell. Cancerous tissue, for example, produces different chemicals than does healthy tissue. Those chemicals will smell different to a cat or dog than those from healthy tissue.
There is at least anecdotal evidence that cats can sense migraines, depression, and diabetes.
A man in Houston reported that the family cat would meow constantly at his teenage son, who has diabetes. She stopped after the boy received treatment and his blood sugar levels returned to normal.
A mother and son in Wisconsin adopted a cat from an animal shelter. When the woman suffered a diabetic seizure, the cat jumped on her chest, bit her nose, and pawed at her face until she woke up and started calling for her son.
The cat then ran into the son’s room and woke him up; the son then called emergency services.
How cats predict epileptic seizures is less clear. They may do it by smell, as with other illnesses, but they could also do it by picking up electrical signals or spotting subtle behavioral changes that presage a seizure.
Why don’t people use cats as illness alert animals the way they use dogs?
Elle di Jensen, a writer for The Nest, notes that there are a growing number of stories about cats that smelled cancer on their owner and tried to warn them about it, often by pawing at the affected area.
Researchers have studied dogs’ abilities to detect illness, and organizations like the Canine Seizure Alert Society of North Carolina have been using such gifted dogs as service animals.
Unfortunately, cats don’t share a dog’s compulsion to smell everything and everyone in their immediate vicinity.
They are also more difficult to train than dogs, at least partly because they don’t always respond to reward-based training as dogs do.
While a dog will eagerly sniff a patient or their urine sample, a cat might refuse. Consequently, few researchers and trainers are willing to work with cats.