National Mutt Day comes twice a year on July 31 and December 2. Like their special days, mixed breed dogs’ genes come in pairs, but exactly which breed those genes came from is often a mystery. Genetic analysis can help veterinarians and pet owners to identify specific nutritional pet food needs or disease risks in mixed-breed dogs, said Angela Hughes, DVM, veterinary geneticist for Mars Veterinary. For pet food manufacturers, DNA analysis could build consumers’ awareness of the need for specialized, therapeutic or prescribed diets and pet treats for mixed breeds.

For example, Hughes told the story of a dog adopted as a puppy from a rescue shelter in California. The new pet parent was told that the dog was a Labrador-Husky mix. The puppy had gastrointestinal issues, and the owner was struggling to find an appropriate food. After GHA confirmed that the mutt was a German Shepherd mix, the owner switched to a food made specifically for that breed, and the dog’s symptoms were relieved.

Mutt-specific pet food and medicine

It’s conceivable that dog owners eventually may be able to select custom pet food blends based on the genetic profile of their particular pet, said Hughes.

Purebred dogs’ nutritional needs and common ailments may be notorious, like hip dysplasia or obesity. However, pet owners may not realize that their mutts can suffer from the same genetic tendencies as the breeds that made up their ancestry. Also, when people adopt a mixed breed puppy, they may not have any idea how large it could grow, and therefor don’t know its nutritional requirements. Genetic testing can help owners know how much and what type of food will help their puppy grow best.

Hughes uses Royal Canin’s Genetic Health Analysis (GHA) to screen dogs for 3,000 genetic markers. Particular breeds are identified by specific combinations of more than 1,800 of those markers. The rest look for genetic disorders. The test can identify more than 250 breeds and types, including US versus UK varieties, 120 genetic disorders and a test for drug sensitivity. GHA can identify a dog’s ancestors back three generations.

In one case, GHA helped a veterinarian identify a breed-specific disease in a mutt. The dog came in to vet’s office with a high fever. The vet was about to run more tests when the dog’s owner mentioned that the dog’s DNA test showed Shar Pei heritage. The vet immediately thought of Shar Pei fever, and treated the mutt accordingly and successfully.

Science behind dog DNA testing

Currently, Mars Veterinary, makers of the GHA, holds the exclusive, worldwide license for the genetic breed detection process. The process was developed and patented by Elaine Ostrander, PhD, and published in the journal Science in 2004. To test a dog, a local veterinarian sends in a blood sample to Royal Canin. The process costs approximately $130 depending on local prices.

In 2010, Mars Veterinary analyzed DNA samples from around the US from more than 36,000 mixed-breed dogs. The DNA analysis found that the 10 most popular breeds showing up in America's mutts, in order, are German Shepherd, Labrador Retriever, Chow Chow, Boxer, Rottweiler, Poodle, American Staffordshire Terrier, Golden Retriever, Cocker Spaniel and Siberian Husky.


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DNA analysis revealed this dog's German Shepherd heritage, then breed-specific nutrition helped this mutt's digestion problems. | courtesy of Royal Canin