People looking to adopt a dog from an animal shelter are usually keen to know what breeds are available.

But they might be better off asking about a dog's behaviour, not breed, as a more reliable way to find a good match between animal and owner, according to the findings of research published Thursday in the journal PLOS One.

A key reason for this is that shelter workers can be wrong a lot of the time in labelling the breed of dogs under their care, even when they follow established guides.

Another reason is that shelter dogs are "complex genetically." Each one is unique, and the researchers say a dog that is a cross of two breeds might not behave much like the typical members of either of its parents' families.

Even if you know the breeds by DNA, it's not really going to tell you what you want to know. - Clive Wyne , researcher

Researchers Lisa Gunter and Clive Wynne from Arizona State University's Canine Science Collaboratory collected DNA from more than 900 dogs at two shelters.

The facilities used were the Arizona Animal Welfare League and Society for the Prevention of Cruelty to Animals (AAWL) in Phoenix, Ariz., and the San Diego Humane Society and Society for the Prevention of Cruelty to Animals (SDHS) in California.

The researchers tested the DNA of Bruce and found he was equal parts of beagle, cocker spaniel and labrador retriever, with the remaining one-fourth a mix beyond three generations. (Arizona State University Canine Science Collaboratory )

ASU scientists genotyped the shelter dogs and compared the genetic information of their assigned breed labels.

The researchers wanted to determine how accurate the labels were at the San Diego shelter, where staff used the physical appearance of a dog and breed descriptions from the American Kennel Club Breed Identification Guides to identify a primary and secondary breed.

When the researchers looked at whether either the assigned primary or secondary breed matched the information from the genetic profile of a dog, they found the shelter staff accuracy was 67 per cent.

The accuracy fell to 10 per cent when staff identified more than one breed.

Stereotyping not helpful

Wynne thinks breed labels should be dropped altogether at shelters, saying "you have a situation where breed-typing is worse than stereotyping members of our own species."

One goal of the Canine Science Collaboratory is the development of a behavioural assessment, to offer something more informative than breed labels.

Researcher Lisa Gunter says shelter dogs are interesting and complex genetically and 'labelling them with a single breed can minimize their uniqueness.' (Shutterstock)

Wynne said breed doesn't necessarily give an accurate prediction of behaviour for a would-be owner, unless they're looking for certain breed-specific things, like pointing.

A simple way to discover if a dog is a good fit would be to foster the animal before deciding on adoption, he said.

Surprising find of genetic diversity

Gunter noted the research found a level of genetic diversity in the shelter dogs that exceeded expectations.

"We found 125 distinct breeds," she said. "We also found that just five per cent of the shelter dogs were purebred, even though it is commonly assumed that up to a quarter of dogs in shelters are purebred."

The genetic testing gave the researchers information about three generations of ancestors for each dog. On average, most dogs were comprised of three different breeds, with some dogs having up to five breed signatures identified at the great-grandparent level.

"There is a 50-50 chance that they'll guess one of the breeds in the dog. The chances of them getting all three right is more or less nothing," Wynne said.

"So people can't tell what the breeds are by looking at the dogs," he said. "And even if you know the breeds by DNA, it's not really going to tell you what you want to know," for having a dog fit in with your lifestyle.

Breed given an 'outsize role'

"Breed identification has quite an outsize role in people's perceptions of dogs," said Wynne, professor of psychology and head of the Canine Science Collaboratory. "'What breed is he?' is often the first question people ask about a dog, but the answer is often terribly inaccurate."

Basing pet selection strictly on a breed label can have unintended consequences for the dog.

For instance, the researchers found that dogs in the San Diego shelter with a pit bull-type ancestry waited more than three times as long as other dog breeds to be adopted.

Because of that finding, which the researchers say was established in a previous study also published in PLOS One, the shelter in Phoenix recently stopped publicizing breed information on their website and on kennel cards, though the breed labels are available upon request.

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