Study uses dog breed, weight, and sex to determine age for early detection of cancer

Almost half of dogs over the age of 10 will develop cancer. However, formal guidelines for earlier detection of cancer through regular screening programs do not exist in veterinary medicine.

New research from PetDx, a San Diego–based molecular diagnostics company that developed a liquid biopsy test for cancer in dogs, provides reference data to help inform the optimal age when cancer screening might be considered in dogs of various breeds and weights. The findings were published Feb. 1 in the open-access journal PLOS One.

Such information may have the potential to improve the ability of veterinarians to detect cancer in the preclinical phase when the disease is more manageable.

English Mastiff dog lying in green summer grass
According to study results, as the weight of the dog increased, the median age at cancer diagnosis decreased. The breed with the youngest median age at cancer diagnosis was the Mastiff at 5 years.

The study, led by Jill Rafalko, director of scientific communications at PetDx, analyzed data from more than 3,000 dogs diagnosed with cancer to determine the age at which dogs of certain breeds and weights are typically diagnosed with cancer. In the study population, the median age at cancer diagnosis was 8.8 years, with males diagnosed at younger ages than females, and neutered or spayed dogs were diagnosed at significantly later ages than intact dogs—8.5 years versus 7.6 years for males and 8.9 versus 7.3 years for females.

The breeds with the youngest median age at cancer diagnosis were the Mastiff at 5 years; Saint Bernard, Great Dane, and Bulldog at 6 years; Irish Wolfhound at 6.1 years; Boxer at 6.2 years; and Vizsla and Bernese Mountain Dog at 7 years. The breed with the oldest median age at cancer diagnosis was the Bichon Frise at 11.5 years.

Overall, weight was inversely correlated with age at cancer diagnosis, and purebred dogs were diagnosed at significantly younger ages than mixed-breed dogs. The combined study population of 3,452 dogs comprised 2,537 dogs reported to be purebred, 858 reported to be mixed breed, and 57 whose breed was described as other.

Many of the breeds with younger ages at cancer diagnosis were large- and giant-breed dogs. In general, as the weight of the dog increased, the median age at cancer diagnosis decreased, with high significance for weight in predicting median age at diagnosis.

Boxers, Great Danes, and French Bulldogs had significantly younger median ages at cancer diagnosis compared with Beagles, Miniature Schnauzers, and Shih Tzus.

To increase the likelihood of early cancer detection and treatment, the authors say, the study’s results support a general recommendation to start cancer screening for all dogs at the age of 7 and as early as age 4 for breeds with a lower median age at cancer diagnosis.