Dog Social Studies – Level 4
In the U.S., mixed-breed dogs outrank purebred dogs in popularity.
By Susan Chaney
The dog is one of the most diverse companion animal species. Hundreds of specific dog breeds have been documented and registered with purebred organizations. Mixed-breed dogs, however, outnumber purebred dogs in the U.S. as the choice for a pet.
A mixed-breed dog comes from one or more parents whose lineage contains more than one breed. Some mutts, as they’re often referred to, may have three or four dog breeds contributing to their physical and temperament traits. Others can have a dozen or more.
According to author Margaret H. Bonham, “People are attracted to mutts because of their [scientifically unproven] hardier reputation and their individualism. When you get a purebred, you know pretty much what you get, but there’s a certain mystery to the mutt. You’re getting a one-of-a-kind.”
Most mixed-breed dogs are the result of unplanned breedings. An unneutered male dog escapes his yard, then almost systematically – using his keen sense of smell – searches the neighborhood for a female dog in heat. When he’s successful, a litter of puppies of potentially unknown pedigree is likely to result.
All dogs have pedigrees. The parents, grandparents, and so on of purebred puppies registered with the American Kennel Club or United Kennel Club are all identifiable. Dogs’ pedigrees also list their date of birth.
Probability dictates that when that dog on the prowl finds a mate-worthy female, at least one of them will be of mixed-breed heritage. It’s unlikely that the mixed-breed dog will have a known pedigree. The family tree of that litter will be a mystery, and each puppy will have an unknown pedigree.
A crossbreed results when two different purebred dogs mate. This breeding may be intentional: The owners of a beautiful Golden Retriever and an amazing Labrador Retriever may decide they’d like a litter of Golden-Labs. Typically, however, such a mating, again, is accidental. Either way, the resulting puppies are not purebred and cannot be registered with any purebred registry, such as the AKC or UKC.
In the last two decades, intentional blending of two dog breeds has become more prevalent. Creating these hybrids or “designer dogs” is often rationalized as an attempt to get the best traits from two different breeds or to create a dog that doesn’t shed and likely will have less dander, causing fewer allergic reactions in people who don’t tolerate dogs well. Such breedings cannot guarantee the intended mix of traits or that a dog won’t shed.
The Cockapoo, a cross of the Cocker Spaniel and Poodle, has been around since the 1950s. Today some Cockapoos are bred to each other. Regardless, they are still not recognized as purebred dogs. Labradoodles (Labrador Retrievers crossed with Poodles) came about as a way to offer non-allergenic assistance dogs for the blind in Australia.
In the last six decades, the practice of intentionally mixing breeds has resulted in the creation of the American Canine Hybrid Club, which will register anything from an “Affenchon” to a “Weshie.”
This practice is much criticized by the majority of reputable purebred dog breeders.
One benefit often touted in relationship to mixed-breed dogs is reduced genetic illness, sometimes called “hybrid vigor” or heterosis.
Whatever term is used, arguments abound on both sides as to whether mixed-breed or purebred dogs are healthier.
In the past, it was common practice to breed related dogs, such as a mother to a son. Over time, this led to numerous breed-specific genetic problems. Reputable breeders, registries, veterinary organizations, and others have taken steps to create testing for many of these conditions and diseases, culling from breeding stock those dogs that would most probably pass them on. Disreputable breeders do not do genetic testing and will use any male and female to create a litter, regardless of the health ramifications.
For these reasons, it’s commonly claimed that mixed-breed dogs are healthier than purebreds. A definitive study has yet to prove that – at least for dogs in the U.S. A 1997 questionnaire study of Danish Kennel Club members found that mixed breeds had a median life span of 11 years, while all dogs in the study lived 10 years. Old age, cancer, behavior problems, and accidents accounted for 47.8 percent of the deaths of the 2,928 dogs in the study.
Purebred dogs vs. mixed-breed dogs
The last five years have seen the development of DNA tests that allow mixed-breed dog owners to find out what breeds flow through their dogs’ less-than-blue blood. Evaluation of a cheek swab or blood sample can identify more than a hundred breeds, revealing the highest concentration of breed DNA, down to the lowest in any given dog.
All dogs alive today are descended from wolves to one degree or another. How and when those wolves became domesticated and were bred for task-oriented traits remain a mystery, though evidence is periodically uncovered pointing to various periods of unrecorded history. Early wolf-dog animals may have been bred for a variety of tasks useful to early humans.
Over time, dogs would specialize in certain work, such as herding, guarding and hunting. The breeds that exist today all find their roots in some kind of work, even if that job is being a companion.
Many modern dog breeds were created in the last 300 years by combining one breed with another to create a desired trait. In that respect, many purebred dogs have more than one breed in their recent family trees. Nonetheless, when a dog results from mating two dogs of the same breed, it is considered a purebred.
 Margaret H. Bonham, The Complete Guide to Mutts (Hoboken, NJ: Howell Book House, 2004) p. 1.
 Karen Bush, Everything Dogs Expect You to Know (Intercourse, PA: Good Book, 2008) p. 27
 Op. cit., Bonham, p. 1.
 Op. cit., Bonham, p. 4.
 Op. cit., Bush, p. 27.
 Op. cit., Bush, p. 42.
 Helle Friis Proschowsky, Helene Rugbjerg, and Annette Kjær Ersbøll, “Mortality of Purebred and Mixed Breed Dogs in Denmark,” Preventive Veterinary Medicine, Vol. 58, No. 1-2 (April 2003): 63.
 Op. cit., Bonham, p. 10.
Susan Chaney was an editor at DOG FANCY magazine for eight years, four of those as the editor. She’s lived with a variety of dogs, both mixed breed and purebred. Today, a Chihuahua-Staffordshire Bull Terrier mix named Max is the apple of her eye.