Can a DNA Test Tell If Your Dog Is Purebred?

A DNA test can tell you whether your dog's ancestry looks like a single breed, but it can't make a dog purebred. In Canada, a purebred dog is one that's registered, or eligible for registration, with an authorized registry such as the Canadian Kennel Club. That's a pedigree record, not a lab result. A breed result that's almost entirely one breed is strong evidence that a dog's recent ancestors all came from that breed, but it isn't a substitute for registration papers.

The short version

• Purebred is a registration status. Under Canada's Animal Pedigree Act, a dog is considered purebred only if it's registered, or eligible for registration, with an authorized registry.
• DNA estimates ancestry. A result close to one breed means your dog's DNA closely matches that breed's reference dogs.
• Breeds are genetically distinct. In a 2004 study, DNA markers alone sorted almost every dog into its correct breed.
• A DNA report isn't a pedigree certificate, and a breed ancestry estimate isn't a parentage test.
• Sellers owe buyers the papers. In Canada, anyone who sells a dog as purebred has to provide its transferred registration certificate within six months.

What "purebred" means in Canada

The Canadian Kennel Club is incorporated under the Animal Pedigree Act, a federal law administered under Agriculture and Agri-Food Canada. As the CKC explains, under that Act a dog is considered purebred only if it is registered, or eligible for registration, with an authorized registry. Registration follows a dog's recorded pedigree: who its parents were, and who theirs were.

The Act also protects buyers. Unless a seller clearly says a dog's registration is from outside Canada, anyone who sells a dog as purebred, registered or eligible for registration has to give the buyer the dog's duly transferred registration certificate within six months of the sale.

So "Is my dog purebred?" has two answers. The legal one comes from the registry. The genetic one, "does my dog's DNA look like a single breed?", is what a DNA test can help with.

What a near-100% breed result means

Purebred dogs are genetically distinct enough for DNA to tell them apart. A 2004 study of 85 breeds found that differences between breeds accounted for about 30% of all genetic variation, and DNA markers alone assigned 99% of individual dogs to their correct breed.

So when a dog's estimated breed mix comes back almost entirely one breed, it's strong evidence that its recent ancestors were all, or almost all, from that breed. A few things are worth knowing:

• Small amounts of other breeds or unresolved ancestry can still appear. Many breeds were built partly from crosses, according to a 2017 study of breed relationships, so closely related breeds share DNA, and the smallest shares are the least certain part of any result.
• A large share of an unrelated breed is different. If a dog sold as purebred comes back with, say, a quarter of another breed, that points to a mixed parent or grandparent rather than to uncertainty.
• It's an estimate, not a certificate. The PuppyGenes report shows an estimated breed mix, including any ancestry that couldn't be resolved. It isn't a pedigree certificate and it doesn't replace registration.

Our guide to breed percentages explains what different shares say about a family tree, and our guide to reading a dog DNA report covers unresolved ancestry.

Why papers and DNA can disagree

Papers record a pedigree; DNA estimates ancestry. They usually agree, but they can come apart:

• A recording mistake or an unrecorded mating somewhere in a pedigree means the papers no longer describe the dog's real ancestry.
• Related breeds share DNA, so small amounts of a closely related breed can appear in a dog whose papers are correct.
• Small shares are uncertain, so a few percent of an unexpected breed is a weak signal on its own.

Parentage questions are a different job. Parentage verification uses DNA tests that compare a puppy directly with its possible parents. A breed ancestry estimate doesn't do that. For more on surprising results, see our guide to DNA results that don't match a dog's looks.

If you're buying a puppy sold as purebred

• Ask about registration up front. In Canada, a seller who sells a dog as purebred owes you the transferred registration certificate within six months of the sale.
• Ask about health testing on both parents. The PuppyGenes report does not include genetic disease or health screening, so it can't stand in for that.
• Use DNA as a cross-check, not as papers. A breed ancestry test can show whether your dog's ancestry looks like the breed you were promised. It can't register the dog. Our guide to DNA testing a puppy covers when to swab and what you'll learn.