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Havanese Club of Great Britain
Genetic Diversity in Havanese
A small breed with a small founding population.
Understanding diversity is not optional — it is the foundation of long-term breed health.
Why Genetic Diversity Matters
The Havanese is a numerically small breed that descends from a limited number of founders.
Like all closed studbook breeds, every generation of breeding draws from the same finite gene pool. When that pool narrows — through repeated use of popular sires, line-breeding, or importing dogs from genetically similar lines — the consequences can take years to become visible, but they are cumulative and difficult to reverse.
Reduced genetic diversity is associated with increased expression of recessive disease genes, reduced immune function and fertility, reduced adaptability to new disease pressures, and inbreeding depression — subtle reductions in vitality, litter size, and lifespan.
The good news is that the Havanese still has meaningful genetic diversity. The goal is to keep it that way — through informed, evidence-based breeding decisions made one litter at a time.
What Population Analysis Reveals
The Royal Kennel Club has commissioned formal population analysis of UK Havanese by RKC Geneticist Joanna Ilska — work that examines the genetic structure of the breed population as a whole, looking at founder representation, how evenly genetic contributions are distributed across living dogs, and where diversity is being lost.
The Veterinary Genetics Lab UC Davis (VGL) and BetterBred, a website and diversity program for breeders, have also carried out a breed assessment of the Havanese using genomic (DNA-based) data, which gives a direct picture of actual genetic relatedness rather than relying on pedigree records and statistical probability calculations alone.
Together, these analyses point to the same conclusion: diversity in the Havanese requires active management.
Some founders are heavily over-represented in the current population; others are under-represented or at risk of being lost entirely.
This is not a crisis — but it is a call to pay attention.
Understanding COI —
and why the numbers matter
What is COI?
COI stands for Coefficient of Inbreeding.
It expresses the probability that a puppy has inherited two identical copies of a gene from a common ancestor — in other words, how closely related its parents are.
The higher the COI, the greater the risk of recessive disease genes being expressed, and the greater the loss of genetic diversity.
The RKC calculator — useful, but limited
The Kennel Club provides a free COI calculator, and we encourage all breeders to use it before every mating. However, it is important to understand its limitations.
The RKC calculator is pedigree-based. It works by tracing known ancestors through the family tree.
The problem is that imported dogs — which make up a significant proportion of UK Havanese breeding stock — are entered into the database with limited pedigree information behind them.
The calculator treats them as completely unrelated to everything else, effectively assigning them a COI of zero.
In reality, many imported dogs come from the same international lines and carry the same genes. This means the RKC calculator can significantly underestimate true inbreeding.
A mating that looks low-risk on paper may be considerably more inbred in practice.
Treat the pedigree COI as a floor, not a ceiling.
Genomic COI — the real picture
Genomic COI is calculated from actual DNA, using thousands of genetic markers across the whole genome.
It reflects true biological relatedness — regardless of what the pedigree records say. The breed average genomic COI in Havanese is considerably higher than the figures typically shown by the RKC calculator.
This is not a criticism of the RKC tool — it is working with the data it has.
But breeders should seek genomic information wherever possible.
Genomic testing through services such as Embark, VGL, or MyDogDNA can give a much more accurate picture of where your dog sits within the breed’s gene pool.
Each Puppy Is Different
A statistical COI applies to the whole litter — it is a prediction of the average level of inbreeding across all the puppies born from that mating.
But each puppy inherits a different combination of genetic material from its parents. Some will be more 'inbred' than the average predicts; others less so.
Genomic testing can measure the actual level of homozygosity in each individual puppy — something pedigree-based calculations cannot do.
This is what makes genomic testing interesting for breeders— it tells you something about each dog that no calculator ever could.
This can also be valuable when selecting a puppy to keep for future breeding, or when advising buyers who may wish to breed — genomic assessment of the litter gives information that the pedigree alone cannot provide.
What to aim for
There is no single “safe” COI figure.
What matters is the direction of travel — each generation should aim to be equal to or lower in COI than the last.
Matings that bring together under-represented lines are particularly valuable to the breed as a whole.