Cover your pup’s ears…did you know that the leading cause of death for adult dogs is cancer?
Researchers at a US diagnostics company, PetDx, have developed a blood test to detect cancer in dogs, which they say could lead to earlier intervention.
Currently, canine cancer is generally identified only after clinical signs have developed, and existing methods of detecting cancer in dogs, including biopsy, x-rays, and ultrasound, are more invasive.
In a new study, published in PLUS ONE, PetDx researchers have determined the median age of cancer diagnosis for dogs with different characteristics, such as breed, weight, and sex. They say the study provides evidence for when to start cancer screening for individual dogs based on their breed or weight.
PetDX suggests that all dogs should begin liquid biopsy cancer screening at age 7, but certain breeds may benefit from screening as early as 4 years.
Professor Rachel Allavena, Specialist Veterinary Pathologist, Associate Director of the School of Veterinary Sciences at the University of Queensland, who is not affiliated with PetDx, welcomes the idea of blood biopsies for our furry friends: Yeah the technology proves to be accurate enough.
Read more: The science behind those irresistible puppy dog facial expressions.
“Screening is well established in people and is highly beneficial to both the population and individuals to detect cancer early when it is treated more easily and effectively, so that the patient has a better outcome,” Allavena said. . Cosmos.
“The authors propose that this approach would be beneficial for domestic dogs.
“While I would sincerely appreciate it if that were the case, major cancers are highly malignant, often difficult or expensive to treat, and even with the best possible treatment will shorten a dog’s life.”
The researchers analyzed data from 3,452 dogs diagnosed with cancer in the US, including more than 120 breeds and a wide variety of cancer types, grades and stages.
Allavena says American dogs are generally comparable to Australian dogs, although there are differences in the prevalence of some types of cancer, presumably due to different genetic groups.
The study found that the median age at cancer diagnosis for dogs weighing 75 kilograms or more was 5 years, compared with 11 years for dogs weighing between 2.5 and 5 kilograms, which may not be surprising given that large breed dogs have a shorter life expectancy than small or tiny breeds. .
“A large dog like a Great Dane, Wolfhound, or Rottweiler might have a typical life expectancy of 8 to 10 years. I have known many more who die much earlier than this from cancer (2-4 years at diagnosis). Whereas a small breed like a Jack Russell would live between 12 and 15 years,” Allavena says.
“That cancer is related to and very common in certain breeds is a well-established phenomenon and something I can confirm as a veterinary pathologist. Much of this is genetic, some of it will also be biomechanical (this is thought to play a role in bone cancer in large dogs).”
By looking at breeds specifically, the researchers were able to determine that Mastiffs, Saint Bernards, Great Danes and Bulldogs had the youngest median age of diagnosis, approximately six years.
Irish Wolfhounds, Vizslas, and Bernese Mountain Dogs had a median age of diagnosis of 6.1 to 7 years, and at the other end of the spectrum, the diminutive Bichon Frize had the oldest median age of diagnosis at 11.5 years.
Interestingly, according to Allavena, in the study “there are some breeds that seem to develop cancer later despite being reasonably sized dogs, such as Beagles.”
The researchers also developed a statistical model to predict the median age at diagnosis based on weight, a model that could be applied to underrepresented breeds in the study and to mixed-breed dogs.
They say their findings suggest that early detection of canine cancer could be improved by starting liquid biopsy testing two years before a dog reaches the average age of diagnosis for its breed or weight.
Would screening make canine cancer treatment more effective or less invasive?
Allavena is cautiously optimistic that if liquid biopsies for dogs are shown to be accurate and affordable, they could benefit dogs, depending on available treatments and how early diseases are detected.
According to a 2022 validation study, the PetDx-developed Onkok9 test has a sensitivity of 54.7%, meaning it can detect true cases of cancer about half the time, and demonstrated a specificity of 98.5 % to avoid detection of false positive cases.
“If we catch them early, can we really benefit the dog by intervening earlier? Is starting chemotherapy earlier going to help? Is doing surgery early going to help? Because a lot of cancers are very common, really nasty, but they often need very complicated and very expensive therapy,” she says.
For osteosarcoma, early diagnosis may mean that limb-sparing surgery may be used instead of the more serious complete amputation.
But, in clinically silent hemangiosarcoma (malignant tumors that originate in blood vessels and often go undiagnosed until a dog dies from it), early detection can only result in removal of the tumor if it has spread to an organ that can be surgically removed (such as the liver). , but not the heart).
Ultimately, he says, veterinary oncology is about quality of life over quantity, so it’s not acceptable to make dogs sick, suffer, or decrease their quality of life by treating them.
“If early detection is going to mean you have a reduced chemotherapy dose or less strong treatment, then maybe that’s a really important benefit of early detection through liquid biopsy.”
