Since more adult dogs die from cancer than from any other cause, detecting canine cancer earlier can enable more effective treatment. Although noninvasive blood tests can now detect tumor DNA long before other signs of cancer arise, formal guidelines for when dogs should be screened using these tests are still lacking.
To help establish such guidelines, a team of scientists led by PetDx – a molecular diagnostics company in La Jolla, California focused on the detection and treatment of cancer in pets – has determined the median age at cancer diagnosis of dogs with different features.
The analysis (which included 3,452 dogs with cancer in the U.S.) revealed that the median age at cancer diagnosis for dogs weighting over 75 kilograms was five years, compared to 11 years for canines weighting between 2.5 and five kilograms. Moreover, the mean diagnosis age for purebred dogs was 8.2, compared to 9.2 for mixed breeds.
Among the breeds analyzed, Mastiffs, Saint Bernards, Great Danes, and Bulldogs had the youngest median diagnosis age (about six years), while Irish Wolfhounds, Vizslas, and Bernese Mountain Dogs had median diagnosis ages ranging from 6.1 to seven years. The Bichon Frise was found to have the oldest median diagnosis age (11.5). Finally, female dogs were generally diagnosed with cancer at older ages than males, and neutered dogs were diagnosed later than intact ones.
The findings suggest that canine cancer detection could be improved through blood test-based screening beginning two years before a dog reaches the median diagnosis age specific to their breed or weight category.
“Dogs now have a new option for cancer screening called ‘liquid biopsy’ which, similar to the human version of this test, leverages next-generation sequencing technology to detect multiple types of cancer using a simple blood draw. However, the age to start screening for cancer in dogs can vary depending on their breed or weight. Our study, involving over 3,000 cancer-diagnosed dogs, found that all dogs should begin cancer screening at age seven, but certain breeds may benefit from screening starting as early as age four,” the authors concluded.
The study is published in the journal PLoS ONE.
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