The notion that dogs are humans’ best friend seems to extend far beyond just emotional bonds in today’s modern world. Pure breed dogs, in particular, are helping modern humans through modern healthcare. Although dogs are known to detect cancer through smell, tumors in purebred dogs are also helping to detect certain types of cancers.
Nearly a quarter of all purebred dogs die of cancer. Since similar symptoms are shown in mice and other animals, further research can help pinpoint why and how to solve these issues. Many purebred dogs are so inbred that they have an increased risk of these genetic factors. Although it isn’t great for disease risk in a closed, small pool of genetics, it is excellent material when studying cancer genetics.
Different breeds are uniquely susceptible to certain types of cancers. Scottish terriers, for example, have a 22% increased chance of getting bladder cancer than the average mixed breed dog. With such an increased risk, it’s likely due to an inherited mutation that has been bred into the group.
Humans themselves are too genetically diverse to trace cancers back to specific mutations, even though around 55% of cancers, like BRCA mutations in breast cancer and APC mutations in colorectal cancer, aren’t due to human habits. Strong familial patterns of disease can allow researchers to look at a small and similar genetic family group. In humans, modern DNA sequencing methods can streamline the process of finding mutations. Interestingly, since all purebred dogs are related to one another like humans are related to our immediate ancestors, every cancer that dogs get is similar to the hereditary cancers in which humans are already aware.
For instance, squamous cell carcinoma of the digit can indicate interbreeding. Squamous cells, or skin cells, and carcinomas are commonly found in breeds like Briards, giant schnauzers, Gordon setters, and Kerry blue terriers. The cancer is spread from too many copies of the KITL gene which is found through the same founder mutation. While not all dog cancers originate from a founder mutation, they seem to share susceptibility.
Another type of cancer, osteosarcomas, is a bone cancer that is fairly rare in humans, but has a high frequency in Irish wolfhounds and great Danes for example. Unfortunately, the genetic makeup that gives these dogs a shared trait of long legs also gives them a predisposition to the disease.
As a result, researchers decided to determine if dogs have mutations in common with one another. Studies showed that dogs often have mutations in two genes, the IL-8 and SLC1A3. Both genes are thought to cause malignant forms of osteosarcomas in humans. With this revelation, researchers can figure out how this cancer forms and spreads, making it much easier on scientists who would have to identify the process through thousands of genes otherwise.
Now, Elaine Ostrander — the chief officer at the National Institute of Health’s Cancer Genetics and Comparative Genomics Branch — is focusing her research on three other diseases including gastric cancer, histiocytic sarcoma cancer, and bladder cancer. The latter, in particular, is of interest because dogs have a high risk of the disease. Gastric cancer is of interest because it’s highly deadly in both humans and dogs. These types of cancer are a high risk for some breeds, but don’t appear in other dogs entirely.
The third cancer in Ostrander’s research group is very rare in humans. However, in Bernese mountain dogs have a 25% chance, while 20% of flat-coated retrievers also are diagnosed with the disease. The cancers arise from blood cells developed separately in these breeds, but the details like how far the tumors spread and the origin differs in each breed. While this isn’t necessarily useful for humans, it’s such a rare form of cancer that it’s useful to understand how mutations affect the profession of these rare cancers. So, the differing factor can help identify the likely cause of these different progressions in each cancer. More research can help determine whether or not those genes might be crucial in the acceleration of certain cancers or where they develop in the body.
As Ostrander and her team study purebreds more, they can hopefully identify more significant ways to treat human cancers. This is where dogs help, too. Dogs help drive cancer research because many similar cancers also occur naturally in dogs, or at least as naturally or as high of a risk as an inbred population can get them, meaning they don’t have to induce any animals with cancer to experiment on ways to cure it. The evidence shows that treatments that work on canine cancers often work on humans, too.
It’s revolutionary and beneficial news for researchers and unnecessary harm to test subjects like rats. The further research progresses, the more it can help prevent cancers in dogs as well as humans. Now, that’s something to bark home about.