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We all know dogs can be used to “sniff out” drugs and explosives and to detect health conditions such as seizures and low blood sugar, but what about sensing the presence of cancer in a patient? Anecdotal evidence of dogs detecting cancer in their owners in the past prompted research into the feasibility of using dogs to detect cancer as part of a clinical setting. As it turns out, scientists and clinicians have had success training dogs to detect odors given off by cancer cells on the breath of cancer patients or in urine or blood serum. It turns out, organic compounds released by metabolism in cancer cells are released in the body fluids of cancer patients and the odor of these substances can be detected by dogs. Dogs trained to signal their detection of these substances can then alert clinicians to the presence of cancer. Amazing!
Although more work is currently being done to develop the accuracy of cancer-detecting skills in dogs and apply it to clinical settings, there is much hope that the ability of dogs to detect cancer or to replicate this ability could be a useful diagnostic tool. Many studies have shown success in training dogs to reliably detect cancer in patients. A poodle named Captain Jennings is being used to help detect ovarian cancer in patients, a particularly invasive and difficult to detect cancer, at the Pine Street Foundation in California.
So how does one teach a dog to detect cancer? Dogs are used to detect the odor of drugs, explosives, and other substances, why not cancer? The metabolites of cancer cells emit an odor that can be detected on the breath or body fluids of cancer patients. There are differences, however, in detecting the scent of cancer as opposed to other scents, as there are hundreds of organic compounds released by cancer cells that dogs need be trained to identify. Training a dog to detect and alert to cancer involves exposing the dog to hundreds of samples containing these organic compounds, and to teach the dog to detect a combination of compounds. Because of the complexity, detection of cancer is most effectively conducted by teams of dogs. A positive hit by multiple members of the team is a good indicator that cancer is present in a patient.
Training a dog to detect cancer involves presenting the dog with hundreds of samples, collected using rigid standards in a clinical setting under strict guidelines, to expose the dog to a wide range of organic compounds that could indicate the presence of cancer in a patient. Organic compounds produced by cancer cells occur in combination with other organic compounds present from the metabolism of non-cancerous cells in the body. A dog with exceptionally sensitive scent-detecting abilities and one of calm focused temperament is required for training to reliably detect cancer under such complicated circumstances.
Training to detect cancer scent, like other scent detection, will involve a reward system to provide motivation for correct identification. Food or play with toys is frequently employed. Also, due to the requirement to distinguish between multiple scents and combinations of scents, the use of a scent wheel containing multiple samples for the dog to distinguish between is employed. Samples consist of samples of blood plasma or urine from a variety of patients, both healthy and with cancer. A scent wheel is similar to a lazy susan with protruding arms holding vials of body fluid. Samples will need to come from multiple people, as using only one person with cancer to train cancer detection will result in training the dog to detect that one person. Instead, hundreds of samples from different individuals are required for training.
The Distinguishing Scent Method
Provide a toy and play with your dog often, use play with the toy as a reward for basic obedience commands.
Set up a scent wheel with two containers, one containing an easily distinguishable scent such as vanilla, and an empty container, or one filled with water.
When your dog approaches the container with the scent to investigate, reward your dog with play with their favorite toy or ball.
Now add an alert your dog can provide you, such as ‘sit’. When your dog identifies the strong scent, ask him to ‘sit’, then reward.
Reward after alert
Start only rewarding the dog with play if they identify the scent correctly and provide the alert.
Gradually add more scents to the wheel.
Teach various scents
Teach your dog to alert to different scents.
Provide cancer scents
Provide multiple samples of blood plasma or urine from cancer patients, and teach your dog to identify and alert to those samples.Reward for correct identification and signal, ignore for false identifications.
The Match to Sample Method
Teach your dog a signal such as ‘sit and look at me’
Provide two articles, one that is scented with a strong scent such as vanilla and one that is not, in front of your dog.
Provide your dog with the vanilla scent on a separate object.
Shape and reward match
Let your dog approach containers with scent. When your dog approaches the unscented object, ignore. When he approaches the scented object, click and reward. Gradually click and reward as your dog gets closer and closer to the scented target object. Repeat exercise multiple times a day for several weeks.
Now give your dog the command for his signal, such as ‘sit and look at me’. Provide command when your dog locates and matches the scented object. Continue to click and reward when your dog successfully matches the scent and signals you by sitting.
Remove command and click
Gradually remove the ‘sit’ command. Gradually remove the click, reward matches and ignore errors.
Start using blood serum samples from cancer patients instead of the strong scent used previously as the target to identify and be rewarded.
Remove provided scent
Remove the sample scent to match to and allow your dog to identify samples from cancer patients without being given a sample scent.
Add multiple samples
Provide multiple samples from healthy subjects and patients with cancer and practice repeatedly for several months.
The Shape Signal Method
Teach your dog a signal such as ‘sit and look at me’ or ‘bow’ that will be used to indicate the presence of the cancer scent. Use a hand signal to command and capture the behavior with a clicker.
Now use the hand signal and provide a scent in a small open container. Start with a strong scent like peanut butter, tea, vanilla or cheese.
When the dog performs the signal in response to the presence of the scent and hand signal, click and reward with food or toy play. Practice several times a day for a few weeks.
Gradually remove the hand signal, continue to present the scent and use the clicker and reward the dog for performing the signal such as ‘sit’.
Transfer to cancer scent
Start presenting blood plasma or urine samples from cancer patients, and transfer the alert response to detecting the cancer scent. Repeat steps 2-4.
Provide multiple scents
Use multiple different samples from cancer patients.
Start providing multiple samples some from cancer patients, some from healthy patients. If the dog alerts to a healthy patient sample, ignore the response, but if they alert to a sample from a cancer patient, reward with treat or toy and play.
By Amy Caldwell
Published: 11/27/2017, edited: 01/08/2021