Dogs have been trained to detect various human cancers, but there haven’t been many studies focused on their capacity to identify cancer in other dogs, which remains limited and yields mixed results. While previous research has demonstrated that dogs can successfully detect malignant tumors from saliva, they have faced challenges in discovering canine urothelial carcinoma (UC) through urine samples.
A groundbreaking study, including collaborators from Medical Detection Dogs, Davies Veterinary Specialists, the University of Bristol, and the Royal Veterinary College, aims to change this narrative by investigating whether specially trained dogs can effectively smell bladder cancer in the urine of other dogs. The findings indicate that this method could be a promising new approach for diagnosing the disease in canines.
In this study, three dogs, already trained to detect bladder and prostate cancer in humans, received specialized training from the charity Medical Detection Dogs (MDD) to detect canine UC through the unique odor of urine.
The results reveal that canine bladder cancer has a distinct odor that these specially trained dogs can detect rapidly and non-invasively, achieving up to 90% sensitivity (correct identification of positive samples) and up to 95% specificity (correctly ignoring negative samples).
Approximately one in four dogs will develop cancer during their lifetime, and, like humans, the incidence increases rapidly with age, so half of all dogs over the age of ten years will develop cancer during their lifetime.
Urothelial carcinoma (UC), also known as transitional cell carcinoma (TCC), is the most common form of bladder cancer in dogs, accounting for almost 2% of all reported canine cancers. The disease can mimic other urinary tract disorders like urinary tract infections (UTIs) and bladder stones, making it challenging to diagnose.
Traditional diagnostic methods, such as cystocentesis—which involves extracting a urine sample via a needle—are often inadvisable as they may cause the tumor to seed. Its resemblance to other, more frequent conditions can sometimes lead veterinarians to mistakenly treat infections when the dog may actually have cancer.
For a definitive diagnosis, a histopathology examination of a biopsy sample is required, which is invasive, costly, and time consuming, thereby delaying the start of treatment.
To combat these challenges, three specially trained dogs—a chocolate Working Cocker Spaniel named Kizzy, a black Cocker Spaniel named Jobi, and a black Labrador named Marlow—were taught to sniff urine samples attached to metal stands in the Medical Detection Dogs’ training room. Their task was to demonstrate specific indication behaviors in response solely to positive (cancerous) samples, which could involve sitting, staring, or standing as a signal.
The dogs were rewarded with food and play for correctly indicating positive target samples and for successfully searching through a negative line without any indication.
The urine samples used for their training were sourced from leftover clinical patients at Davies Veterinary Specialists, as well as healthy dogs belonging to Medical Detection Dogs and staff and volunteers of the charity.
“We have proven many times that dogs can detect cancer in human samples, so we are confident that they would also be able to smell it in those from other canines,” said Claire Guest, CEO, Co-Founder, and Chief Scientific Officer at Medical Detection Dogs.
“We are delighted that they were so successful at finding the odor of bladder cancer as it is a difficult disease to diagnose using traditional methods and unpleasant and intrusive for canine patients.
“When they do get diagnosed, the disease is often advanced, so there is great potential value in a new, early, cheap, rapid, and non-invasive diagnostic test, which could lead to opportunities for earlier intervention than is possible at present. Dogs are way more than only man’s best friend.”
“This study adds to the growing body of evidence which shows dogs are highly effective at detecting odors from changes linked to health in both humans and canines,” added Dr. Nicola Rooney from Bristol Veterinary School at the University of Bristol, and one of the study’s authors.
“The dogs involved with the study demonstrated a sensitivity superior to the cytology of a free catch sample and similar to the BRAF test,” said Isabelle Desmas-Bazelle, who spearheaded the study. “It suggests cancer cells have a unique odor pattern, possibly via secretion of volatile organic chemicals. This exciting research could lead to the development of an electronic nose as an additional diagnostic test for UC.”
Journal reference:
- Isabelle Desmas-Bazelle, Nicola Jane Rooney, Steve Morant, Rob Harris, Veerle Volckaert, Mark Goodfellow, Sophie Aziz & Claire Marie Guest. Trained dogs can detect canine urothelial carcinoma of the bladder. Veterinary Oncology, 2024; DOI: 10.1186/s44356-024-00012-1