Can dogs really detect diseases? It seems to make sense. We know a dog’s nose is 1,000 to 10,000 times more sensitive than ours (depending on what study you’re looking at); if they can find missing persons, leaks, drugs, smoke, cadavers, bombs and chemicals, why not cancer, diabetes and seizures?
Scripps Clinic gynecologist Robert Gordon uses his Chihuahua to detect disease in urine samples. Ginger wasn’t 100% accurate, but she got it right more than half the time over 250 trials. Can your doctor beat this?
The question seems to be: do diseases have their own smell? According to Gordon,
“There’s evidence that certain solid tumors of the breast, prostate, lung or bladder may discharge volatile or aerosolized compounds such as formaldehyde, benzene or alkanes or a mix and that these are distinguishable from odors caused by inflammation, bleeding or infection due to other health problems.”
Some years ago, the British medical journal Lancet published a letter from a London dermatologist who spoke of a patient, a woman whose dog seemed overly interested in a lesion on her leg. He would sniff and then bite at it. The woman sought the doctor’s advice, and a diagnosis of malignant melanoma was found.
Gordon decided to test dogs on prostate and breast cancers, “because they’re such common killers.” He set up a laboratory in his garage and procured some dogs – Ginger came from Petco, along with $7,000 to help finance the operation. Other interested parties raised another $20,000. Gordon contacted cancer patients and after obtaining Scripps’ approval, began experiments on them, and a control group of well people.
Not long after, the results of a study reported in the British Medical Journal gave Gordon a boost: the authors also used urine samples to train dogs to sniff out bladder cancer. On their finals, the dogs tracked the disorders 41% of the time: more than chance alone would allow.
Gordon denied his methods were a cure-all. He said a lot of questions remain unanswered, principally surrounding the researcher’s methods. One thing he feared was that the dogs were simply memorizing a certain urine smell, as the team was forced to use the same samples over and over due to lack of available samples. Or, that the dogs might be responding to unconscious cues given by the trainers as they neared the suspect sample, a la “Clever Hans.”
Gordon’s co-author Lawrence Myers, a professor of veterinary medicine at Auburn University in Alabama, admitted their trials have a critical test to pass:
Another question is whether the dogs are responding to unconscious body movements or muscle tension they perceive in their owners when they get near the correct specimen.
Lawrence Myers, Gordon’s collaborator and a professor of veterinary medicine at Auburn University in Alabama, specializes in behavior and sensory function in detector dogs. He said Gordon’s work still has to pass a critical test.
“Unless it’s done as a double blind study, in which the trainer doesn’t know the the correct answer, it doesn’t count. Otherwise there’s still a very real possibility that there was unintentional cueing. You can demonstrate this fairly readily even among people who think they’re being oh so very careful – their body tension, a low sound, anything of that sort.”
Even the pens Gordon used to mark the specimens came into question: he realized at one point that he was marking the urine of cancer patients with a different color. Also, they speculated the dogs might be influenced by the smell of their chicken reward (Gordon kept pieces of chicken in his pocket for this purpose) on the investigators’ hands as they set up the samples.
But does cancer in its various stages smell the same? Can dogs detect and mark the especially lethal cancers – those that grow swiftly and often kill? Gordon decided to use gas chromatography to try to identify just what the dogs were responding to. “Some people are trying to develop electronic noses – machines that can sniff and make diagnoses. But no one has improved upon the dog’s ability to smell. Studies are ongoing.
A 66-year old diabetic lady we’ll call “Emily” owns a dog named Candy. Emily had been having frequent hypoglycemic episodes, during which she would sweat profusely, feel extremely weak, anxious, and irritable. Emily usually tends to these attacks promptly. But at one point, she noticed that Candy was acting strangely. She would jump up, run to another room and hide under a chair. Once Emily had consumed some carbohydrates, Candy rejoined her. Emily then noticed that Candy anticipated these attacks before she herself did.
Another case studied involved a seven-year old dog called Susie and her mistress, who also had hypoglycemic episodes. Susie somehow was able to sense an episode coming on – even when her owner was asleep – and nudged her awake. Susie persisted in this behavior until her owner consumed carbohydrates. She wouldn’t allow her mistress to leave the house until she had eaten something.
In a study reported in the UK in 2004, researchers started with the assumption that dogs can indeed detect cancer. This study also used urine samples from healthy people, people with other diseases, and well people. The dogs they used, ordinary house pets, were able to identify the cancer urine “Three times more often than would be expected by chance alone,” according to the authors.
Tim Cole, a professor of medical statistics at the Imperial College in London, had this to say:” The issue is not whether or not they can detect cancer, because clearly they can. The issue is whether you can set up a system whereby they can communicate with you. That requires further ingenuity.”
Bladder and prostate cancer surgeon David Neal, at Cambridge University in England, believes it is plausible that dogs can sniff out cancer, as sufferers shed “unique abnormal proteins in their urine.”
Other English doctors reported in 2001 a case where a man who had suffered from eczema for 18 years, noticed his dog sniffing at the disturbed skin, even through his trousers. The man was diagnosed with skin cancer. What was interesting was that once the tumor was removed the dog showed no further interest in the leg.
In another study (stay with me here!) two cocker spaniels named Tangle and Biddy claimed a success rate of an astounding 56%! The other amazing thing about this study was that the dogs persistently “marked” urine from a healthy person, even though tests had shown no sign of cancer. Persuaded by the dogs, the doctors tested in more depth and sure enough, the man had a malignant tumor in the right kidney.
Cats have even been known to detect disease. Susi Johnson, a diabetic, says her cat, Ichabod, can tell when her blood sugar is getting low. Ichabod nudges, slaps her face, or even bites her until she gets up and checks her insulin level – “Sure enough, it’s low,” she says.
So the next time you catch your dog rolling ecstatically in something putrid, give thanks for the famous doggy detection system. It might just save your life!