December 10, 2024, 8:38 am | Read time: 4 minutes
Dogs have a keen sense of smell and can even sniff out tumors. A study has now successfully demonstrated for the first time that these four-legged friends can also sniff out bladder cancer in other dogs. This type of cancer is particularly aggressive and is usually detected too late. A smell test by dogs could contribute to a faster diagnosis.
It’s a well-established fact that dogs have the ability to detect cancer through scent. Consequently, these canine companions have been successfully utilized for years in the early detection of various human cancers. Theoretically, dogs should possess the capability to detect cancer in their fellow canines as well. Nonetheless, the limited research available on this subject has yielded varying conclusions.
British researchers at the University of Bristol have now, for the first time, provided evidence that dogs can reliably identify bladder cancer in their conspecifics through the analysis of urine samples. PETBOOK summarizes the exciting results that were published in the veterinary journal Veterinary Oncology.
Valuable Time Passes Between Suspicion and Diagnosis
While bladder cancer constitutes approximately two percent of all canine tumor diseases, it is notably aggressive and frequently metastasizes. Consequently, early detection is paramount for the successful treatment of this condition. However, bladder cancer is not externally visible and manifests solely through symptoms.
Urinary dysfunction is among the most prevalent indicators of this malignant tumor. Nevertheless, urinary dysfunction can also be symptomatic of other conditions, such as cystitis or bladder stones. To definitively diagnose the cancer type, a histopathological examination of a biopsy sample is necessary.
Such an examination is not only costly but also carries associated risks. In addition, valuable time elapses between taking the sample and receiving the final result, which can delay the start of treatment.1
Dogs Can Identify Cancer in Humans
Claire Guest, CEO, co-founder, and Chief Scientific Officer of Medical Detection Dogs, said in the online specialist magazine Phys.org: “We have proven many times that dogs can detect cancer in human samples, so we were confident that they could also smell it in other dogs.” To test this, the researchers used three dogs for their study that were already able to sniff out bladder and prostate cancer in humans.
The test dogs, a chocolate-colored working cocker spaniel named Kizzy, a black cocker spaniel named Jobi, and a black Labrador named Marlow, were trained to sniff out transitional cell carcinoma in urine samples. This carcinoma is the most common type of tumor in bladder cancer.
Can Dogs Also Smell Cancer in Conspecifics?
To find out, the scientists placed various urine samples in metal racks. These came either from
- healthy dogs without urinary tract abnormalities (control),
- from dogs with non-malignant urinary tract diseases (control) or
- from dogs with transitional cell carcinoma (positive).
The dogs were trained to signal the presence of positive samples by either staring, sitting, or standing in front of them. Negative samples were to be disregarded, with the dogs expected to simply walk past them. When the dogs correctly identified the samples, they received rewards in the form of food or play sessions, which occurred with notable frequency.
Dogs Indicate Bladder Cancer with 90 Percent Certainty
The dogs demonstrated the ability to accurately identify positive samples with a certainty of up to 90 percent. With a certainty of up to 95 percent, the dogs consistently disregarded negative samples. The researchers’ conclusions from the study indicate that bladder cancer in dogs emits a distinct odor, which can be swiftly and non-invasively detected by dogs with specialized training.
“We are delighted that they were so successful in finding the odor of bladder cancer,” Claire Guest shares in the Phys.org article. Bladder cancer represents a condition that poses diagnostic challenges when relying on conventional methods. Additionally, the biopsy procedure is distressing for the affected animals. “Guest further explained that by the time bladder cancers are diagnosed, the disease has often progressed significantly, underscoring the substantial potential value of a new, early, cost-effective, rapid, and non-invasive diagnostic test.
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Dogs are More Reliable Than Laboratory Analysis
The study suggests that dogs can be trained using appropriate methods to detect cancer caused by transitional cell carcinoma in conspecifics from urine. This could serve as an additional non-invasive diagnostic test for the disease, the researchers conclude in their study.
Isabelle Desmas-Bazelle, who spearheaded the study at Davies Veterinary Specialists and currently serves as a lecturer and co-head of oncology at the Royal Veterinary College, elucidated in Phys.org that the dogs not only outpaced laboratory analysis in speed but also surpassed it in reliability. “This implies that cancer cells emit a unique odor signature, potentially due to the release of volatile organic compounds. This groundbreaking research holds the promise of paving the way for the creation of an ‘electronic nose’ as an ancillary diagnostic tool for transitional cell carcinoma.”
“The researchers express their anticipation that, with enhanced screening protocols, increased sample sizes, and stringent control of potential confounding factors, the performance of sniffer dogs will surpass the already impressive results demonstrated in this initial study. This could ultimately allow cancer to be detected earlier and, therefore, treated earlier than is currently possible.