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.