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Old 09-24-2009, 12:00 PM
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Sniffing Out Cancer
By Narda G. Robinson, DO, DVM, MS, FAAMA

Going in to a doctor’s office to have a suspicious lump checked? Imagine your surprise at finding at your doctor’s side an assistant wagging a tail and sniffing you vigorously. Is this more pleasant than just about any other diagnostic screening? Yes. As reliable? Possibly.

While some may shudder at the thought of being analyzed for cancer by a wet nose, the brain attached to that nose does an amazing job of sorting “normal” from “abnormal.”

In addition to cancer, sniffer dogs can signal hyper- and hypoglycemia and possibly seizure activity. As written by the authors who first talked about canine cancer sniffers, “The adjunctive use of animals with highly developed sensory modalities in cancer diagnosis is worth considering—and is infinitely better than using dogs to study tobacco carcinogenesis.”

It all began in 1989, when dermatologists broke their story in The Lancet about a 44-year-old woman whose border collie/ Doberman mix incessantly sniffed, and one time tried to bite off, a thigh mole confirmed histologically as malignant melanoma.1

They explained, “This dog may have saved her owner’s life by prompting her to seek treatment when the lesion was still at a thin and curable stage.”

What unfolded from there has created a mystery that leaves researchers scratching their heads. The canine tumor tattling that started with skin lesions (melanoma and basal cell carcinoma) extended to breast and lung cancer and even urinary tract neoplasia.

The dogs don’t need to see the lesions; they can find the problematic moles under clothing.2

The tissue doesn’t need to be living; one of the first accounts of in-vitro tumor sniffing took place in Florida, where a dermatologist teamed up with a former police- and military-dog trainer who taught a Schnauzer named George how to recognize in-vitro malignant melanoma tissue based on conventional sniffer-dog techniques.3
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For cancer, better screening leads to longer lives, as does tighter glucose control for diabetics.
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Once, George examined a patient harboring several supposedly cancer-free moles and became “crazy” after sniffing one of them. Subsequent analysis confirmed the lesion as an early malignancy.

Once word spread about this “pet scan” cancer screening, reports surfaced about dogs smelling out other types of cancer. One physician wrote, “I had encountered a patient who claimed that her dog’s incessant sniffing led to her finding a breast mass that proved malignant.

Owing to the lack of substantiating literature to back up her claim, most of her medical team brushed this off as coincidence, particularly since the lesion was internal rather than cutaneous as in other anecdotal reports.”4

These anecdotes led to controlled trials. In 2004, investigators performed a proof of principle examination of whether dogs could identify which patients had bladder cancer by smelling their urine samples. Dogs outperformed chance by a nearly three times higher correct response rate, deemed highly significant.5

One commentator wrote about how dogs in training consistently pointed to a control patient’s urine as cancer-positive, even though the patient’s cystoscopy and ultrasound did not indicate cancer. The dogs’ focus on the sample caused the investigator to look again, this time finding a kidney carcinoma.6

More studies followed. This included recruiting dogs to sniff out cancer from the exhaled breath of patients who had lung and breast carcinoma.7

Their ability to identify lung cancer had a sensitivity and specificity of 0.99.

They caught breast cancer with a sensitivity of 0.88 and 0.98 specificity.

The stage of disease was relatively unimportant. Training took place over a matter of weeks and involved “ordinary household dogs with only basic behavioral ‘puppy training.’ ”

Most recently, a double-blind test series showed that dogs successfully discriminated between different histopathological types and grades of ovarian carcinomas and normal tissue.

Sensitivity and specificity rates were 100 percent and 97.5 percent, respectively.8

It mattered not whether the tissue was early stage, low grade or advanced. Fat from the same individuals who contributed the carcinoma did not test positive.

How do they do it? No one knows for sure.

Volatile organic compounds in the exhaled air may explain some of the findings,9 but not the zeroing in on the body surface overlying a breast lesion or of sniffing out a melanoma through trouser legs.

Dogs’ remarkable talents do not stop there. They appear able to detect precipitous declines in blood glucose, allowing rapid intervention before a loss of consciousness ensues.10

A forensic scientist who trained dogs for law enforcement became one of the first to identify dogs as hypoglycemia sniffers. His dog was alerted when he experienced an episode of severe hypoglycemia.

The scientist then tested the dog using a sweater that a diabetic had been wearing during a hypoglycemic episode, and it sniffed positive.

Dogs can likewise alert to hyperglycemia, allowing those fortunate enough to live with a trained dog to maintain a much tighter control over their blood sugar levels, no longer needing to fear going too low. 11

How do these dog hypoglycemia detectives announce their findings? By causing a raging ruckus—jumping, running in the house, hiding under chairs, pacing, pawing at the person or putting their head in the person’s lap until the hypoglycemic individual ingests sufficient carbohydrates to normalize their blood glucose.12

It’s hard to miss or ignore their agitation.

Is there something that the dog’s brain, from olfactory receptor to central nervous system to behavioral display, can assemble that will be quicker, less expensive and more accurate than laboratory analyses?

For cancer, better screening leads to longer lives, as does tighter glucose control for diabetics. Might some of the health-care dollars of the future be rightly dedicated to train and develop canine cancer catchers and bad-blood sugar barkers?

As the editor of one journal reporting on these stories pondered: “So what if the canine nose is more accomplished at detecting cancer or predicting seizures or hypoglycemia than our most refined instruments? …

How much proof must we acquire before employing such non-toxic diagnostic methods in pursuit of covert cancer cells, or to portend a hypoglycemic event or convulsions?”13

Narda Robinson, DVM, DO, Dipl. ABMA, FAAMA, oversees complementary veterinary education at Colorado State University.

This column first appeared in the Septemer 2009 issue of Veterinary Practice News


1. Williams H and Pembroke A. Sniffer dogs in the melanoma clinic? The Lancet. 1989;1:734.

2. Church J and Williams H. Another sniffer dog for the clinic? The Lancet. 2001;358:930.

3. Church J and Williams H. Another sniffer dog for the clinic? The Lancet. 2001;358:930.

4. Welsh JS. Another cancer detected by “pet scan”. BMJ. 2004;329:1286.

5. Willis CM, Church SM, Guest CM, et al. Olfactory detection of human bladder cancer by dogs: proof of principle study. BMJ. 2004;329:712-714. Cited in Cole TJ. Commentary: teaching dogs new tricks. BMJ. 2004;329:715.

6. Cole TJ. Commentary: teaching dogs new tricks. BMJ. 2004;329:715.

7. McCulloch M, Jezlerski T, Broffman M, et al. Diagnostic accuracy of canine scent detection in early- and late-stage lung and breast cancers. Integrative Cancer Therapies. 2006;5(1):30-39.

8. Horvath G, Jarverud GAK, Jarverud S, et al. Human ovarian carcinomas detected by specific odor. Integrative Cancer Therapies. 2008;7(2):76-80.

9. Ligor M, Ligor T, Bajtarevic A, et al. Determination of volatile organic compounds in exhaled breath of patients with lung cancer using solid phase microextraction and gas chromatography mass spectrometry. Clin Chem Lab Med. 2009;47(5):550-560.

10. Wells DL, Lawson SQ, and Siriwardena AN. Canine responses to hypoglycemia in patients with Type 1 diabetes. Journal of Alternative and Complementary Medicine. 2008;14(10):1235-1241.

11. Spake A. Could a dog save (Your Life?} Diabetes Forecast. 2008; 61(3):40-47.

12. Spake A. Could a dog save (Your Life?} Diabetes Forecast. 2008; 61(3):40-47.

13. Benda W. Nature’s child [Editorial]. J Alternative and Complementary Medicine. 2008;14(10):1177.
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Last edited by FurKids; 09-24-2009 at 12:30 PM.
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