Some may think that the Great Dane, the breed of the puppy in this photograph, is the tallest dog breed in the world, but it’s actually slightly less than the Irish Wolfhound. This belief probably stems from a Guinness World Record for the tallest dog in the the world which still belongs to a Great Dane named “Zeus” who measured 3 feet and 8 inches in height before he passed away. Before Zeus, Great Danes named “Gibson,” “Titan,” and “George” held the title.
Stanford University has reported that dogs are now the physically most diverse land animal, but many physical traits are determined by very few genetic regions. In fact, according to Stanford professor of genetics, Carlos Bustamante, only six or seven locations in the dog genome are necessary to explain about 80 percent of the differences in height and weight among dog breeds. Put another way, the differences between a Dachshund and Great Dane may not be genetically all that complicated.
The average person may find this of only passing interest, but this kind of information helps researchers understand human traits, the idea being that identifying the dozen regions where dogs house genetic switches among breeds will provide clues about where researchers can find mutations important to human health and disease.
Fact is, breed standards, kennel club regulations, and breeders have led to isolated populations of breeds with minimal gene flow between them. This provides a gold mine of information to scientists. The highly respected researcher at the National Institutes of Health, and chief of its Cancer Genetics and Comparative Genomics Branch, Elaine A. Ostrander, says that thorough record keeping amongst dog breeders, a breed’s viability as a cancer research tool is enhanced because “it facilitates both association analysis and family-based linkages.” She argues, as well, that the days of maintaining dog colonies at veterinary schools started with limited founders for the purpose of studying a single cancer type, are past. Instead, owners, breeders, geneticists, and veterinarians can work together to design highly accurate studies using pet dog populations.
A 2013 study by researchers at the University of California, Davis, found that mixed breeds weren’t fundamentally healthier than purebred dogs when it came to inherited canine disorders, and this was was a helpful to scientists because dogs are second only to humans in the number of identified genetic disorders that affect them. We finish with another quote from Dr. Ostrander: “For the most part, dogs get everything we do. You see some striking similarities that you don’t see in mice or other animal models, and that makes them an increasingly terrific system to study the genetic basis of disease.”
Read more about how purebred dogs are helping us cure cancer here.