Dogs are our friends, surrogate babies, exercise buddies, protectors, work mates and support companions, but sadly they can die from many of the conditions that beset humans, including cancer.
More adult dogs die from cancer than from any other cause.
And just as in humans, detecting canine cancer earlier can enable more effective treatment.
New, non-invasive blood tests for dogs can detect tumour DNA long before other signs of cancer arise.
However, formal guidelines for when dogs should be screened using these tests are lacking.
A new analysis has determined median ages of cancer diagnosis for dogs with different characteristics, providing support for the establishment of cancer screening guidelines that vary according to breed or weight.
The researchers found dogs' average age at cancer diagnosis was associated with size, sex and breed.
They found that the median age at cancer diagnosis for giant breed dogs weighing 75 kilograms or more was five years, compared to 11 years for dogs weighing 2.5 to 5 kilograms.
The mean diagnosis age for purebred dogs was 8.2 years, compared to 9.2 years for dogs whose breed was described as mixed or "other."
The analysis involved 3452 dogs with cancer in the US
Among breeds with enough representation in the study, the researchers determined that mastiffs, Saint Bernards, great danes and bulldogs had the youngest median diagnosis age, at about six years. Irish wolfhounds, vizslas and Bernese mountain dogs had median diagnosis ages of six to seven years. At 11.5 years, the bichon frise had the oldest median diagnosis age.
Female dogs were typically diagnosed at older ages than males, and dogs that were neutered were diagnosed later than intact dogs.
The researchers also developed a statistical model to predict median diagnosis age based on weight, which could be applied to breeds with less representation in the study and to mixed-breed dogs.
The researchers propose canine cancer detection could be improved through blood test-based screening beginning two years before a dog reaches the median diagnosis age for their breed or weight.
The findings were presented in the open-access journal PLOS ONE.
