Researchers are nearly finished mapping the genome of the boxer, a dog so inbred it makes European royal families look positively diverse. The boxer blueprint may give scientists a better model for human genetics than the lowly laboratory rat.
"This really gives us an opportunity to understand the genetics of human biology and disease," said geneticist Elaine Ostrander of the Fred Hutchinson Cancer Research Center in Seattle.
In a press conference and panel discussion attended by well-behaved live dogs, Ostrander and colleagues from around the country touted the value of canine genetics at the annual conference of the American Association for the Advancement of Science in Seattle.
Partly as a result of their interaction with humans, dogs have evolved into the most diverse mammals on the face of the earth – not to mention one of the most disease-ridden species anywhere. Hundreds of breeds of Canis familiaris – perhaps 400 or more – have weights that can vary by as much as 100 times from the tiny Chihuahua to the mammoth Saint Bernard. By comparison, other mammals (including you and me) come in smaller ranges of shapes and sizes.
Dog colors, personalities and other traits also differ between breeds to an extent that goes well beyond the mostly cosmetic differences that separate the human races. Specific genes may account for the intelligence of some breeds or the willingness of others to follow instructions. The two traits can be mutually exclusive. The Irish wolfhound, for instance, loves to do what it's told, but, according to one speaker, it "takes the short bus to school" in the brain-power department.
"The challenge is to try to figure out what genes are responsible for this amazing amount of variation," Ostrander said.
Like humans, dogs suffer from a long list of diseases, including some ailments that plague specific breeds, such as deafness among Dalmatians and glaucoma in basset hounds. Nine of the 10 most common medical ailments among dogs also attack humans, including cancer, epilepsy, auto-immune disorders and heart ailments. (The exception is the descriptively named dog disease called bloat.)
The $46 million federally funded boxer genome project should be finished by summer. The purebred nature of Tasha, the boxer in question, may give scientists a better glimpse of dog genetics than the roughly mapped genome of a poodle named Shadow.
Findings so far suggest the dog is genetically closer to humans than the mouse is. Because of their longstanding friendship, dogs and men may have faced similar evolutionary pressures, said Gordon Lark, geneticist at the University of Utah. Human dog breeders sped up canine evolution and, in the process, doomed many breeds to develop their own trademark illnesses and bequeath them to future generations. About 400 genetic diseases have been diagnosed in dogs.
Not all the answers to questions about dog genetics will be found in canine genomes. Some are buried in a long ago past. Biologists suspect that dogs evolved from the gray wolf about 100,000 years ago, and became domesticated in the last 15,000 to 50,000 years, after humans realized they made good companions.
It's not clear, however, whether humans domesticated dogs separately on different continents or developed furry friendships in one place (perhaps East Asia or the Middle East) and then brought the dogs to the New World over the old Arctic land bridge.
Anthropologists have found 9,000-year-old dog skeletons in America, some frozen in the Arctic permafrost. But the oldest domestic dog remnants were discovered in central Russia. At least two dogs have been discovered, and both are big, looking like Great Danes or mastiffs, said University of California at Los Angeles geneticist Robert Wayne. Carbon dating suggests they roamed with their humans about 15,000 years ago, torpedoing theories that domestic dogs evolved later.
Will dogs meet the fates of countless laboratory rats and mice in the effort to unravel the wonders of dog diversity and their genetic similarity to people? After all, dogs – particularly beagles – are already put to death in labs after undergoing experiments. Could more canine testing be on the way?
The researchers at the Seattle conference, dog owners themselves, promise that America's pooch population is safe.
"It's possible to do dog genetics without ever having a dog in a laboratory situation," said Lark, the University of Utah geneticist. Indeed, dog owners contribute to genetics projects remotely by sending in samples of their pets' DNA.
And when sick animals are studied, Lark said, "we can use the same parameters of privacy, individuality and caring that you use for human disease."
Seattle dog owner Dana Baldinger hopes Lark is right. She is director of Japanese Chin Care and Rescue Effort, devoted to one of the smallest dog breeds in the world – the chin, or Japanese spaniel.
"If they can help people without lab testing, it could be a great thing, and I like the potential it has for the medical problems that dogs have," said Baldinger, who brought a 12-week-old black-and-white Japanese chin named Fanny to the Seattle conference in a tiny carrier that gave new meaning to the term "doggie bag."
Researchers expect that the decoding of the dog genome will help veterinarians treat ailing Akitas and sick Shar-Peis. But knowledge has its limits.
"As far as we know, there's no gene for peeing in the house or eating your shoes," said College of Charleston biologist Norine Noonan. In other words, canine gene therapy will only go so far.