This Silent Killer Has a Smell and Dogs Can Find It Before Vets Can
Cancer remains one of the leading causes of death in both people and pets. In dogs alone, studies suggest that up to half will develop cancer during their lifetime. Among the most devastating diagnoses is hemangiosarcoma, an aggressive cancer of blood vessel cells that often goes undetected until it is too late.
Hemangiosarcoma has earned the reputation of a silent killer. Many dogs appear completely healthy until a sudden collapse caused by internal bleeding from a ruptured tumor, most commonly on the spleen. By the time the disease is diagnosed, treatment options are limited and prognosis is poor.
Currently, there is no reliable screening test to detect hemangiosarcoma early. That reality is what drove researchers at Penn Vet to ask an innovative question. Does hemangiosarcoma have a distinct scent that trained dogs can detect?
The answer, according to new research published in The Veterinary Journal, appears to be yes.
Following the Scent
The study was led by Cynthia M. Otto, professor of working dog sciences and sports medicine at the University of Pennsylvania School of Veterinary Medicine and executive director of the Penn Vet Working Dog Center. Working alongside her was Clara Wilson, a postdoctoral research fellow at the center.
At the heart of the research is the concept of volatile organic compounds. These compounds are what humans and animals actually smell.
“We are picking up on volatile organic compounds every time we smell something,” Wilson explains. “Dogs can detect them at much lower levels than we can. These compounds seem to be key to how dogs are able to identify diseases like cancer.”
Previous studies have shown that dogs can detect certain human cancers, including ovarian and pancreatic cancer. The Penn Vet team wanted to know whether the same principle could apply to hemangiosarcoma in dogs.
How the Study Worked
Five trained bio-detection dogs participated in the study. These dogs had prior experience detecting odors associated with other diseases, including chronic wasting disease, post-traumatic stress disorder, and multiple forms of human cancer.
The dogs were tested using blood serum samples collected from three groups of dogs: those with confirmed hemangiosarcoma, those with non-cancerous diseases, and healthy controls. Importantly, none of the samples used during testing had been part of the dogs’ initial training.
The trials were conducted in a double-blinded manner using olfactometers, which are highly specialized scent detection devices.
“These machines use an infrared laser beam across the top,” Wilson explains. “When the dog breaks the beam, it registers that the dog is investigating the sample. If they remain in the beam long enough and it is the correct sample, they hear a tone and know they have earned a reward.”
Each dog evaluated multiple sets of samples across several trials, allowing researchers to measure accuracy and consistency.
Encouraging Results
Across all trials, the dogs correctly identified hemangiosarcoma samples about 70 percent of the time.
“That level of accuracy falls right in line with what we see in studies where dogs are detecting human cancers,” Wilson says. “Cancer is an incredibly complex smell, so this is very encouraging.”
While the study was not designed to create an immediate clinical screening tool, it successfully demonstrated something critical. Hemangiosarcoma does appear to have a detectable scent profile.
That finding alone is a major step forward.
Why Early Detection Matters
If hemangiosarcoma could be detected earlier, the implications for patient care would be significant.
“If we could identify it before a tumor ruptures, we could intervene sooner,” Otto explains. “That might mean removing the spleen before catastrophic bleeding occurs or starting chemotherapy earlier. It is the spread of this disease that is so devastating.”
Wilson adds that a scent-based screening tool could potentially be used as part of annual wellness care.
“It could serve as an early flag,” she says. “If a dog screened positive, the veterinarian could follow up with imaging such as ultrasound or CT. Right now, we are simply finding this disease far too late.”
Earlier detection could also open doors for research. Identifying hemangiosarcoma sooner would allow veterinarians and scientists to evaluate new treatments in clinical trials, something that is often not possible once the disease has progressed.
“This is an initial kernel of hope,” Wilson says.
Looking Ahead
The long-term goal is not to place dogs in every clinic as diagnostic tools. Instead, researchers hope that understanding the scent profile of hemangiosarcoma could lead to the development of a machine-based test that replicates what trained dogs can detect.
Such a tool could transform how veterinarians approach one of the most feared diagnoses in canine medicine.
“This work has the potential to change outcomes,” Otto says. “Not just by helping us catch disease earlier, but by giving us the opportunity to test better treatments and ultimately save lives.”
About the Researchers
Cynthia M. Otto is a professor of working dog sciences and sports medicine in the Department of Clinical Sciences and Advanced Medicine at the University of Pennsylvania School of Veterinary Medicine. She also serves as executive director of the Penn Vet Working Dog Center.
Clara Wilson is a postdoctoral research fellow at the Penn Vet Working Dog Center.
Additional authors include Molly Buis, Samantha Holden, Julianna King, and Amritha Mallikarjun, all of Penn Vet.
Funding and Support
This research was supported by the American Kennel Club Canine Health Foundation, with contributions from multiple breed foundations and charitable organizations. Additional funding was provided by the American German Shepherd Charitable Foundation and the Rookie Fund. Sample provision was supported by the Morris Animal Foundation.
As veterinary medicine continues to push the boundaries of early detection and prevention, studies like this offer a powerful reminder that innovation sometimes starts with something as simple, and as extraordinary, as a dog’s nose.
