How Do Dog DNA Tests Work? From Saliva to Report

A dog DNA test works by reading your dog's DNA from a cheek swab and comparing it with DNA from reference dogs of known breeds. The patterns your dog shares with each reference breed become a breed-ancestry estimate, and the versions of specific genes it carries become trait predictions. The results are probability-based estimates, not a pedigree record or a direct reading of every gene.

The short version

1. Collect: you swab saliva from your dog's cheek pouch and post the sample.
2. Extract: DNA is extracted from the sample at the lab.
3. Read: the DNA is read at positions where dogs differ, using a genotyping array or sequencing.
4. Compare: the readings are compared with a reference panel of dogs of known breeds.
5. Estimate: the comparisons become breed percentages, trait predictions and a diversity result, each with its own uncertainty.

Step 1: From saliva to DNA

A cheek swab collects saliva and the cells that come with it, and those cells carry your dog's DNA. For the PuppyGenes kit, you collect saliva from your dog's cheek pouch for about 30 seconds, after skipping food for 30 minutes and water for 10 minutes. No scraping and no blood draw are needed. Inherited DNA is present from birth, so age doesn't change the ancestry or trait results. For puppies, we suggest waiting until they're fully weaned, and our guide to DNA tests for puppies covers timing.

At the lab, DNA is extracted from the sample. PuppyGenes uses a U.S. lab partner, and report data is stored in Canada and handled in line with PIPEDA.

Step 2: Reading the DNA

Dogs share almost all of their DNA, so a test focuses on the positions where dogs differ. Most of those are single-letter differences called SNPs. There are two common ways to read them:

• Genotyping arrays, or SNP chips, read a fixed set of positions chosen in advance.
• Sequencing reads DNA letters directly. Low-pass sequencing reads positions across the whole genome thinly and fills in the rest by genotype imputation.

The PuppyGenes report combines sequencing evidence with reference-based predictions. Sequencing evidence is combined with canine reference data to estimate ancestry, included traits and genetic diversity, and an inferred result is not a definitive direct reading of every genetic position.

Step 3: Comparing with reference dogs

Breed ancestry rests on a simple fact: dogs of the same breed share DNA patterns, because breeds were founded from limited groups of dogs and then bred within the breed. A 2004 study of 85 breeds found that differences between breeds accounted for about 30% of the genetic variation among the dogs it sampled. Later work mapped 1,346 dogs from 161 breeds into 23 clades of related breeds.

A test compares your dog's DNA with its reference panel, the set of dogs of known breeds it uses for comparison, and estimates which breeds your dog's DNA most resembles. In the PuppyGenes report, your dog's DNA is compared with a curated reference panel and reported as estimated breed percentages. Our guide to reference panels explains why the panel's make-up matters.

Step 4: Turning comparisons into estimates

The comparisons become the sections of a report. The PuppyGenes report has six:

• Breed ancestry: estimated breed percentages. Smaller contributions and closely related breeds can carry more uncertainty.
• Coat colour: possible colour, pattern and markings where the evidence supports them.
• Physical appearance: predictions for coat and body features, each shown with its own confidence.
• Temperament and size predictions: breed-informed tendencies and an estimated adult height and weight.
• Genetic diversity: a genotype-based inbreeding estimate, compared with dogs in the reference panel.
• Oral microbiome: a snapshot of the bacteria measured in the sample.

These are probability-based estimates, not pedigree records, and the report does not include genetic disease or health screening. Our guide to reading a dog DNA report walks through every section.

Why some results come back uncertain or unavailable

Every result depends on the evidence in the sample and on the reference data behind it, so confidence varies by result and some measurements may be unavailable. Common reasons include:

• Closely related breeds, which can be hard to tell apart.
• Small ancestry contributions, which carry more uncertainty than large ones.
• Limited reference data: the reference panel does not represent every dog population.
• Traits the sample can't settle: in Juno's example report, the merle result reads "could not be determined".

If a result surprises you, our guide to DNA results that don't match looks explains the usual reasons, and our science page sets out what each section can and can't tell you.

How long it takes

Results usually arrive within 4–6 weeks of posting your sample. Kit delivery is separate, and exact timing can vary. Our guide to how long a dog DNA test takes breaks down each part of the journey.