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Alaskan Sled Dogs: Genetics of Canine Athletes

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Four Siberian Huskies with blue and brown eyes pulling a sled in a snowy landscape.

When we think of Alaskan sled dogs, breeds like the Siberian Husky, Alaskan Malamute, or even the Samoyed usually come to mind. These are the types of dogs popularized by movies like Snow Dogs, White Fang, Balto, and Togo. But according to Dr. Heather Huson, many other types of dogs can be modern sled dogs, too.

A slide titled "Sled dogs" showing various dogs, from Huskies to hounds, that are all considered Alaskan sled dogs.

All these dogs are considered modern sled dogs, including the breeds that we don’t typically think of as sled dogs. Source: “Alaskan Sled Dogs, the Genetics and Selection of Elite Canine Athletes” presented by Dr. Heather Huson at the 2022 Canine Health Summit.

Heather Huson, PhD, Associate Professor of Animal Genetics at Cornell University, studies sled dogs and the unique genes that give them their athletic abilities. She raised sled dogs for 23 years and has participated in internationally sanctioned events throughout the United States and Canada.

Dr. Huson joined Embark at the second annual Canine Health Summit to talk about why Alaskan sled dogs are their own breed, and how genetic testing through Embark helped her uncover some of the genes that make sled dogs such elite athletes.

Types of sled dog racing

There are two broad types of sled dog racing: distance and sprint. Distance racing is a test of endurance. Distance races involve hundreds of miles, with the long-distance race called the iditarod clocking in at 1,000 miles.

If distance racing is a marathon, sprint racing is a track-and-field competition. Sprint racing applies to races that are between 3 and 30 miles. Even though 30 miles might seem like a long distance, it’s actually considered short for a trained sled dog.

Ancestry of Alaskan sled dogs

Modern sled dogs are mixed-breed dogs. They have some ancestry in Arctic breeds, but they also have ancestry in other breeds like Greyhounds and Pointers.

To understand the origins of modern Alaskan sled dogs, Dr. Huson studied their genetic ancestry the same way Embark does—through genotyping

The biggest finding from Dr. Huson’s study shows that genetically, Alaskan sled dogs are a breed of their own. They aren’t officially recognized by the American Kennel Club, and they don’t have specific breed standards. But because of the intense selection for athletic performance, modern sled dogs do have their own unique genetic signatures that make up their breed.

“Alaskan sled dogs are their own genetic breed, just as distinct as a Poodle, a Chihuahua, or a Labrador Retriever.” —Dr. Heather Huson, Associate Professor of Animal Genetics, Cornell University

Dr. Huson also found that Alaskan sled dogs carry genetic ancestry associated with several known breeds. The five most common breeds she found in modern sled dogs include Siberian Husky, Alaskan Malamute, English and German Shorthaired Pointers, and the Saluki.

How Alaskan sled dogs became elite canine athletes

Dogs that are considered “elite” athletes have a high percentage of Alaskan sled dog ancestry in their breed mix. Their genetic ancestry also influences their athletic performance. Dr. Huson tested sled dogs’ DNA for genetic associations with speed, work ethic (the dog’s drive to run and pull), endurance, and heat tolerance.

While all these elite athletes had Alaskan sled dog as their dominant genetic breed, several other breeds are associated with their athletic traits. Dr. Huson found that dogs that had high endurance had more Siberian Husky and Alaskan Malamute ancestry. Dogs that had high heat tolerance had higher German Shorthaired Pointer ancestry.

Unique genetic traits of Alaskan sled dogs

To dive deeper into the genetics behind heat tolerance, Dr. Huson looked at the DNA of dogs who performed well in the heat and dogs who performed better in the cold.

She found a variant in the myosin 9 gene on chromosome 10 that codes for superior heat tolerance. Dogs with this variant tend to race well even in higher temperatures compared to other sled dogs.

Not surprisingly, German Shorthaired Pointers—and sled dogs with German Shorthaired Pointer ancestry—commonly have this variant for superior heat tolerance.

The link between “wheezer” disease and blue eyes

Dr. Huson is interested not only in the genetics of athletic performance, but also in making sure that Alaskan sled dogs stay healthy. She investigated several health conditions affecting sled dogs, using Embark dog DNA tests.

Congenital laryngeal paralysis is commonly referred to as “wheezer” disease due to the wheezing sound that affected dogs make when they breathe. Dogs generally show signs of this condition between 6 weeks and 9 months old.

This disease affects many other breeds, not only Alaskan sled dogs. But wheezer disease has a significant impact on Alaskan sled dogs and their ability to perform.

Alaskan sled dogs with wheezer disease tend to also have blue eyes, which are coded by the gene ALX4. In fact, Embark made the discovery that identified the ALX4 variant explaining why dogs have blue eyes!

Using a genome-wide association study, Dr. Huson found that the blue-eyes gene, ALX4, is in the same region of chromosome 18 that is associated with wheezer disease. 

“We don’t know if the disease is associated with the same gene as blue eyes,” says Dr. Huson. “We think it probably is. But we still don’t know which mutation is the culprit.”

Embark health tests for Alaskan sled dogs

Dr. Huson trusts Embark dog DNA tests in her research. She tests her Alaskan sled dogs using exactly the same Embark Breed + Health Kit that you can purchase online.

“We took all the genetic health traits that Embark provides, and asked, ‘what’s in sled dogs?’” —Dr. Heather Huson

Of all the 210+ genetic health risks that Embark tests for, Dr. Huson found that the genetic results that stood out the most in Alaskan sled dogs include Alaskan Husky Encephalopathy, ichthyosis, and low ALT activity. She also found that the sled dogs who have the genetic variant for ichthyosis also tend to get harness rub, a type of chafing that can occur when a dog wears a harness for long-distance races.

“The interesting thing is, ALT is also related to energy metabolism. We’re now looking at ALT to figure out how it’s related to energy and if it’s also related to dogs’ athletic performance.” —Dr. Heather Huson

Watch Dr. Huson’s full talk:

Helping dogs live longer lives

Currently, Dr. Huson is working on the Vaika Project, which aims to help dogs live longer lives and improve their well-being. She’s studying 104 retired sled dogs from all over North America to better understand the science of aging. 

Some of the dogs look like Huskies and some resemble hounds. You can meet the dogs, read their stories, and watch their daily activities.

A slide titled "Sled dogs" showing various dogs, from Huskies to hounds, that are all considered Alaskan sled dogs.

Some of the retired sled dogs enjoying playtime at their new home at Cornell University. Source: “Alaskan Sled Dogs, the Genetics and Selection of Elite Canine Athletes” presented by Dr. Heather Huson at the 2022 Canine Health Summit.

Watch the Canine Health Summit

Interested in more fascinating insights about dogs and health? You can watch all the sessions from the Embark Canine Health Summit on demand.

Mimi Padmabandu Contributor

Mimi Padmabandu is a scientific writer and Senior Content Strategist at Embark Veterinary. Her career includes a decade of experience writing about science and genomics for leading biotechnology companies, including Illumina, Thermo Fisher Scientific, and more. She holds a degree in Molecular, Cell, and Developmental Biology from UCLA and a master’s degree from King’s College London.

Read more about Mimi Padmabandu

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