What should puppy buyers know about inbreeding in purebred dogs?

Many people assume that buying a purebred dog means buying a healthier or more predictable dog. Are purebreds more predictable than a mutt? Yes, purebreds have that corner of the market covered. That is what attracts us to pure breeds. We want predictable traits.

However, scientific research shows that high levels of inbreeding are widespread in purebred dogs, and this can have serious health consequences.

Multiple genetic studies have examined how closely related dogs are within their breed (Dreger et al. 2016; Donner et al. 2018; Bannasch et al. 2021; Mata and Mata 2023 Subramanian and Kumar 2024). These studies consistently show that inbreeding is common across most dog breeds.

One of the largest studies, by Bannasch et al. (2021), analyzed the genetic coefficient of inbreeding (COI) for 227 of the most common dog breeds. The researchers found that the average COI across these breeds was 0.249 (24.9%). To put this into perspective, a COI of 25% is what you would expect from a brother–sister mating in a population with no prior inbreeding. In other words, the average purebred dog today is genetically as similar as the offspring of two siblings.

You might think this average is skewed by just a few extremely inbred breeds, but the data show otherwise. According to Bannasch et al. (2021):

• 108 breeds have an average COI of 25% or higher (the level of full sibling mating)

• 47 breeds are closer to 25% than to 12.5% (the level of a half-sibling mating)

• 46 breeds are above 12.5%, though not closer to 25%

• 16 breeds are closer to 12.5% than to 6.25% (the level of a cousin mating)

• Only 8 breeds are just above cousin-level inbreeding (6.25%):

Australian Labradoodle (6.4%), Bolognese (9.0%), Danish-Swedish Farm Dog (7.9%), Koolie (7.9%), Kritikos Lagonikos (7.5%), Norrbottenspets (9.0%), Parson Russell Terrier (7.9%), and Tamaskan Dog (8.5%)

Just one breed in the study had an average COI slightly below cousin mating levels:

• Rat Terrier (6.0%)

For comparison, mixed-breed dogs averaged a much lower COI of 3.7%, well below cousin-level inbreeding (Bannasch et al. 2021, appendix). Earlier research found similar results (Dreger et al. 2016; Beuchat 2016).

While it is encouraging that a small number of breeds have lower inbreeding levels, the overall picture is concerning. According to standards such as those used by the Swedish Kennel Club, cousin-level inbreeding (6.25%) is often considered the maximum acceptable limit. Yet in Bannasch et al.’s study, only one out of 227 breeds even approaches this level. In Sweden they are analyzing the pedigree calculations of inbreeding. Unfortunately, this historic measurement of inbreeding has been proven to be a false narrative. These same purebred dogs have a drastically higher level of inbreeding than their pedigrees show.

More importantly, research shows that health problems linked to inbreeding can begin at levels above 5% (Beuchat 2016). This means that even the least inbred purebred breeds studied are still above the threshold where inbreeding-related risks increase.

How do I get a puppy who is not inbred?

For puppy buyers, the wide-spred inbreeding highlights why it is important to look beyond labels like “purebred” and to ask breeders informed questions.

Ask questions about DNA tested genetic diversity, disease testing and not just pedigree papers with pedigree analysis of inbreeding. The pedigree will NOT show the compounded genetic inbreeding.

Purebred dogs are far more inbred than what a pedigree shows in the typical 12 generation pedigree analysis. Why? Because the ancestors are all also closely related. Learn more on his subject where we documented DNA tested inbreeding vs Pedigree inbreeding of our Golden Retrievers.

Are there any Golden Retrievers who are less inbred?

In some breeds we can reduce the inbreeding by pairing dogs from opposite gene pools. As and example, this can be achieved in Golden Retrievers by pairing a dog from European show lines with American hunting lines. Due to both families of dogs not sharing any ancestors for many decades, the inbreeding can greatly reduce in the puppies. But, this method does not apply to all breeds, especially small population breeds where all dogs in the world are closely related. As of January 2026 the only platform for comparing two parent dogs DNA tested COI is Embark. A breeder can check the DNA tested COI prediction of the litter prior to ever producing puppies. The second and not as accurate option for Golden Retrievers is using UC Davis VGL diversity testing and then utilizing the BetterBred platform with these results. The VGL platform does a great job with Haplotypes but does not do a great job with overall inbreeding between the two dogs. The BetterBred option of using Interrelatedness is a start to help a breeder know who is or is not a good pairing, but this format is not nearly as accurate or user friendly as Embark DNA COI.  Learn more about the options of genetic diversity testing. 

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The effect of inbreeding, body size and morphology on health in dog breeds by Danika Bannasch et. al., 2021

Full study link:

Bannasch D, Famula T, Donner J, Anderson H, Honkanen L, Batcher K, Safra N, Thomasy S, Rebhun R. The effect of inbreeding, body size and morphology on health in dog breeds. Canine Med Genet. 2021 Dec 2;8(1):12. doi: 10.1186/s40575-021-00111-4. PMID: 34852838; PMCID: PMC8638537.

These three pictures of Dataset 1 show all of the 227 dog breeds analyzed in the study: The effect of inbreeding, body size and morphology on health in dog breeds. Bannasch et. al. 2021
The pictures show the DNA tested COI score and how many dogs were analyzed per breed. As an example, in Golden Retrievers, 1617 dogs were DNA tested and the range of inbreeding was 27%-28%.