What cancer research scientists learned working with dogs helped save the life of a 12-year-old Pasadena boy who had less than a year to live when bone cancer had spread to his lungs. He was successfully treated with an experimental drug that had been developed to treat bone cancer in dogs at Colorado State University.
CSU is one of twenty major animal oncology centers participating in an innovative cancer epidemiology initiative following more than 3,000 Golden Retrievers, from birth to death, now entering its 13th year.
Each of the dogs in the study is some human’s beloved dog companion, with one of the study’s goals to develop cancer treatments that will help both species. Researchers estimate humans and dogs share 400-500 genetically identical diseases. We also share the same environment, exposing us to the same carcinogenic triggers.
Comparative oncology is a relatively new field of study that compares naturally occurring cancers in companion animals to human cancers to understand similarities and differences in tumor development, progression, and response to treatments. The human cancer death rate in the United States is less than 20 percent. It accounts for around 27 percent of mortality in all dogs. Due to their inbred nature, in purebred dogs, it’s higher, about 32 percent. But in some breeds, it’s extremely high, the Golden Retriever being one of them.
A health report published in 1999 by the Golden Retriever Club of America identified cancer as the cause of death in 61.4 percent of their dogs. The high incidence of cancer is a relatively recent phenomenon. In a 1988 health study conducted by the University of Pennsylvania School of Veterinary Medicine, the Golden Retriever cancer rate was 38.9 percent.
Cancer is a broad term for a complex cluster of more than a hundred diseases, most of which humans share with dogs. Although there are many causes, most start with alterations in genes that tell cells how to function, which trigger accelerated and uncontrolled cell growth. The defective signal may hide in genes inherited from parents or germinate when normal genes are exposed to harmful environmental influences.
Population, popularity, and popular sires
Although other pedigreed dogs are at high risk for cancer, Golden Retrievers are an ideal study group because their population exceeds that of most other breeds. The larger the sample size, the more accurate the data. Additionally, because these versatile dogs perform multiple jobs—from assistance and search-and-rescue work to field, competitive performance, and companion tasks—they are subject to a broad range of environmental exposures.
The Golden Retriever is a relatively modern breed, developed in Scotland in the mid-19th century and registered in the UK in 1903, about the same time the dogs were imported to the U.S. In 1925, Goldens were registered with the American Kennel Club, and by the 1950s, the affable sporting breed had gained popularity in this country. Today, they are the third most popular breed. An estimated 500,000 registered dogs (and likely ten times that number that are not AKC registered) live in the US.
Registration agencies impose strict standards on pedigreed dogs, requiring that the ancestors of each dog be registered as well. This, combined with the widespread use of popular sires, means that each breed is a closed population with no gene flow. The “popular-sire” effect occurs when an animal with desirable attributes is bred repeatedly. Descendants share specific genetic mutations, both good and bad, and those mutations spread rapidly throughout the gene pool, where they may become permanently established.
Looking for answers
When the 1998 study confirmed that a high number of Goldens were dying of cancer, breeders realized they had both a tragic problem and a unique opportunity. In 2012, the group partnered with Morris Animal Foundation, a non-profit organization that bridges science and resources to advance the health of animals worldwide. They established the first breed-specific, life-to-death longitudinal research project of its kind, identifying Golden Retriever owners from all 48 contiguous states so a broad geographic region could be represented in the data and samples would better represent all dogs living in the United States.
Owners and veterinarians complete yearly online questionnaires about the health status and lifestyle of the dogs to identify the nutritional, environmental, and genetic risk factors for cancer and other diseases. Annual physicals are required, and biological samples are collected regularly. Could one solution be as straightforward as avoiding environmental triggers that trip biological switches and activate uncontrolled cell growth? Maybe.
Researchers expect to collect enough data to accurately show relationships between exposures and the following four killer cancers: lymphoma, a whole-body cancer; mast cell inoperable skin tumors; osteosarcoma, a bone malignancy; and hemangiosarcoma, an aggressive cancer that invades the spleen and heart. These fatal cancers begin to increase in incidence around five to six years and peak at about age nine or ten. However, they may also develop in dogs aged two and younger.
Moving the goal line
The original study goal was to have environmental and clinical data along with biospecimens over time from at least 500 Goldens that died from cancer, a sad milestone reached in 2023 when the dogs were only between eight and 11 years old. The deaths were expected. However, scientists were extremely surprised to discover that more than 63 percent of these fatalities were from only one of the four primary target cancers, hemangiosarcoma, a disease that may begin in bone marrow cells and then spread very rapidly to the heart and spleen. Dogs show no discomfort, rarely giving the owners any clue that their dog is harboring a fatal disease until the tumor ruptures. Within hours, the dogs experience profound internal bleeding, often dying before the owner even knows the dog is sick. In response, the Foundation launched a multimillion-dollar project, the Hermangiosarcoma Initiative, that dedicates funding, people and resources to advance the prevention, detection and treatment of, and potentially cures for, this devastating cancer in dogs.
The future
Though the initial cohort of 3,044 dogs has now decreased to 1,127, the Foundation continues to raise funds to follow all the study dogs for the rest of their lives, regardless of disease or diagnoses. This large collection of prospective data and samples is available to researchers by request and at no charge to help spur more studies seeking to address canine cancer and other health challenges in dogs.
As the Golden Retriever Lifetime Study enters its 13th year, the Foundation has collected 3 billion genetic data points, 65 million non-genetic data points, and 615,000 biological samples. About 1,365 of the dogs are deceased, with 66 percent of those deaths being cancer-related.
Although scientists are just beginning to scratch the surface, as of July 2024, more than ten research papers have been published, and many more are in the works. The population-based study is creating a baseline for research that’s available to scientists worldwide to help not just Golden Retrievers but all dogs, and because we share most of the same diseases, eventually, people as well.
As a former guide dog school administrator who worked with Golden Retrievers for many years until they all but disappeared from training programs due to early onset cancer, I look forward to seeing them return to assistance work in the near future. The breed has a remarkable work ethic and a love of people, always ready to help anyone in need. It feels good to know that when they need us most, we’ve been there to meet the challenge.
Read more about the Morris Animal Foundation Golden Retriever Lifetime Study
