ROCKVILLE, MD, April 5, 2007 – From the smallest Chihuahua to the largest Great Dane, dogs dramatically vary in size, much more than most other animals. Now scientists have discovered a genetic basis for this diversity.
A new study published in tomorrow’s edition of the research journal Science reveals a genetic marker that may determine whether dogs are big or small, and helps answer a burning question in genetics – how could dogs as a species have such a tremendous variation in size?
“This study is a major milestone in canine genetics, made possible by the help of thousands of dog owners around the world. Together with a team of leading international researchers, we have precisely located the major gene that produces our miniature breeds,” said co-author Paul G. Jones, PhD, a genetics researcher at Mars – a world leader in pet care that has been researching canine genetic science for the last seven years.
Dogs were one of the earliest animals to be domesticated more than 15,000 years ago, although people and wolves have coexisted for some 400,000 years. While all dogs originated from wolves, which are of a fairly standard size and appearance, modern dog breeds display a wide diversity of traits, including size. The genetic origin of this diversity has baffled scientists, who have been trying to explain how and why size differences occurred so rapidly in dogs. It is now thought that a change in the gene detailed in the new study resulted in the appearance of small dogs in the population many thousands of years ago.
Jones said it is likely that people soon saw the benefits of smaller dogs, for example for protecting food stores from vermin or catching small game. This further strengthened the bond between people and dogs and led to increasing popularity of smaller dogs as companions.
The international team of researchers – ranging from scientists at the National Human Genome Research Institute, Cornell and other leading universities in the U.S. to Mars scientists in the United Kingdom – used 3,200 dog DNA samples provided by Mars Incorporated, which holds the most comprehensive canine genetic database in the world. This has been built up with the help of pet owners who consent to their pets providing saliva and blood samples for the database. Mars’ genetic data allowed the study to fill the gap between giant and miniature breeds ensuring coverage across the entire range of sizes of breeds we have today.
“These findings are just the tip of the iceberg in canine genetics,” Jones said. “We are well on our way to identifying additional genes that can provide valuable insights into our pets.”
With the dog genome now fully mapped, scientists are discovering a range of potential benefits of DNA-based information on man’s best friend.
"The ability to isolate a specific genetic marker in such a quick and effective manner has tremendous implications for the future," Jones said. “Applications of this cutting-edge science could be used to develop products that will benefit the health of pets – for example, developing individualized preventative care plans for dogs that are susceptible to certain diseases will help pet owners and veterinarians. In addition, genetic information about size and behavioral traits, such as trainability and temperament could also help veterinarians identify the most lifestyle-appropriate pet for an owner."
Mars is continuing its commitment to canine genetic science with ongoing investigations to better understand the makeup of a dog’s DNA to help benefit the lives of dogs and pet owners.
Source: Sutter NB, et al. A single IGFI allele is a major determinant of small size in dogs. Science. April 6, 2007.
About Mars Inc.
A privately-held company, Mars, Incorporated produces some of the world's leading confectionary, food, pet food, health and beverage brands, and operates in more than 65 countries. Headquartered in McLean, Virginia, Mars, Inc. employs close to 40,000 associates worldwide with 100 manufacturing facilities globally. In Europe, Mars, Inc. employs more than 15,000 associates. The company owns some of the world's favorite brands including MARS®, M&M'S®, SNICKERS®, DOLMIO®, UNCLE BEN'S®, PEDIGREE® Brand Food for Dogs and WHISKAS® and SHEBA® Brand Food for Cats. The company's global sales exceed USD 19bn. annually. For more information, visit mars.com.
About Mars Veterinary™
Mars Veterinary is the newest division of MARS® Incorporated, a company known for innovative consumer and pet food brands that are trusted by people around the world. Mars Veterinary is developing sophisticated genetic tests that allow pet owners, veterinarians and care providers to gain insight into the genetic make up of their individual dog. It is reaching new frontiers in canine genomic science, discovering important genetic markers that will help identify breed mixes, predispositions to specific diseases, and determinants of physical and behavioral traits. Through research into pet genetics, Mars Veterinary is dedicated to revolutionizing personalized pet care by strengthening the bond between people and their canine companions. For more information, visit marsveterinary.com.
About Science
Science is the world’s leading journal of original scientific research, global news and commentary. The journal is a publication of the American Association for the Advancement of Science (AAAS).
Dog Facts
Dogs have one of the widest variations in size of any species. The adult bodyweights of the largest breeds are up to 70 times more than those of the smallest breeds. According to the American Kennel Club, in 2006 the most popular large-breed dogs in the USA were the Labrador Retriever, the German Shepherd Dog and Golden Retrievers; the most popular small-breed dogs were Yorkshire Terriers, Dachshunds and Shih Tzus.
Journal
Science