The Alaskan Sled Dog - A Genetic Breed Apart

The Alaskan Sled Dog - A Genetic Breed Apart

Heather Huson and her Alaskan sled dog Kestrel.

Heather Huson has a passion for sled dogs. She grew up participating in sled-dog racing, qualifying twice for the U.S. team, and competing in the sport's world championship of sled-dog racing in 1995 and 2001.

Now the National Human Genome Research Institute (NHGRI) graduate student and University of Alaska Fairbanks Ph.D. candidate has found another place for sled dogs: in her genetics research.

Huson is the lead author of a study on the genetic origins of sled dogs, a study that also includes authors from NHGRI's Cancer Genetics Branch and her university advisor. In their analysis of 199 Alaskan sled dogs and 141 other breeds, the study found that Alaskan sled dogs represent a distinct genetic breed, characterized by performance and behavior rather than appearance. The study is published in the July 22, 2010 online issue of the BioMed Central's open access journal BMC Genetics.

"The Alaskan sled dog presents a case in which a genetically distinct breed of dog has been developed through the selection and breeding of individuals based solely on their athletic prowess," Huson said. "Interestingly, this continual out-crossing for athletic enhancement has still led to the Alaskan sled dog repeatedly producing its own unique genetic signature. Indeed, the Alaskan sled dog breed proved to be more genetically distinct than breeds of similar heritage such as the Alaskan Malamute and Siberian Husky."

Dogs have been used for pulling sleds in the arctic region for hundreds of years. Over the past 50 years, sled-dog racing has become a high performance sport that has influenced the kind of dog that is harnessed into a team. In the modern era, the working sled dog has been bred with fleet-footed breeds like the English Pointer and the German Shorthaired Pointer to enhance the athletic performance desired, whether for sprints or long-distance sled races.

Heather Huson and her team of Alaskan sled dogs race in the Alaska Dog Mushers Association Challenge Series in Fairbanks, Alaska. Her team are the same genetic breed, but reflect the physical appearance of breeds that have contributed to their genomes.

Consequently, the animals that Huson and others in her sport assemble as a team can be dissimilar in appearance, with traces of Shepherd or Pointer or Husky. To look at Huson's sled-dog team, for example, the team that helped her capture first place in the 2004 Tok Race of Champions, you might suspect her dogs to be not a common breed. Some have short fur, others long fur, while some have a trace resemblance to Irish Setters and others to German Shepherds. But, depending upon the type of race, it's sprinting ability or race endurance that are the traits sought by mushers such as Huson. It helps if the animal has a strong work ethic as well.

In the study, Huson and her colleagues sampled sled dogs from eight kennels, rating them for speed, endurance, and work ethic, using established criteria specified for the distinct racing styles of sprint and distance. An assessment of work ethic was made by observing the tension of the tugline that attaches an individual dog's harness to the main team line. These attributes were correlated with genetic information taken from each dog and compared to likely ancestor breeds.

The new insights about performance and breed origin were derived from a DNA analysis of 96 markers in the canine genome. The researchers compared Alaskan sled dog DNA with data from 141 similarly genotyped purebred dog breeds. Their findings confirmed that the Alaskan sled dog has a unique molecular signature and that the genetic profile is sufficient for identifying dogs bred for sprint versus distance.

Moreover, the researchers could identify contributions from existing breeds to the Alaskan sled dog profile. The Alaskan Malamute and the Siberian Husky contribute enhanced endurance, the Pointer and the Saluki are associated with enhanced speed and the Anatolian Shepherd demonstrates a positive influence on work ethic.

According to the study, this research has set the stage for mapping studies aimed at finding genes that are associated with athletic attributes integral to the Alaskan sled dog. Huson also notes that canine performance research, particularly a high performance breed like this one, is instructive in gaining genomic insights about metabolic systems important for muscle rehabilitation, which could help people suffering from physically disabling diseases or traumatic injuries.