The current state of the breed.
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The most recent health surveys place the median age of death for Flat-coats between 7.4 and 9.8 years.
For every Flat-coat living a normal lifespan of 12-13 years, there is one dead by 6.
Data suggests Flatcoat longevity is declining over time.
For more information on Flatcoat longevity, check out our Resources page. -
Health survey results confirm the breed’s sad reputation, with cancer serving as the primary cause of death. Flatcoats have a relative risk of developing cancer 5 times that of all other breeds. In one recent study, only one breed - Irish Water Spaniels - suffer higher rates of reported cancer deaths.
When aggregating survey data, we learn that over 50% of Flat-coat deaths are attributed to cancer, with an especially high prevalence of histiocytic sarcoma (HS) and hemangiosarcoma. A Flat-coat Cause of Death Register managed by Dr. Jane Dobson reports that 70% of entries are attributed to “tumor or cancer-related.”
A 2021 study led by Dr. Evans of the Cancer Genetics and Comparative Genomics Branch of the NIH investigated Flatcoat’s genetic predisposition to histiocytic sarcoma, identified 18 genes on two loci, and estimated that 90% of UK Flatcoats and 70% of North American Flatcoats have undesirable genotypes. It is also notable that when researchers wish to study HS, an otherwise rare cancer in the animal kingdom, they turn to Flatcoats and Bernese Mountain Dogs because of their predictably high rates of this otherwise rare disease.Cardiac issues are also a notable killer in the breed, accounting for 12% of deaths recorded in the Register.
It is also worth noting that we do not otherwise see particularly high rates of the Mendelian inherited diseases present in many breeds.
For more information on Flatcoat health data, check out our Resources page.
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Long-lived Flat-coat parents do not reliably produce long-lived offspring. An analysis of the Flatcoat Data website tells us that, while there is a very weak correlation between parent and offspring age of death, there is no correlation when cancer is the cause of death. Selecting for longevity is, unfortunately, not a viable option for reliably perpetuating healthy dogs. This also helps explain why a dedicated and attentive breeding community has not successfully improved the breed’s health outcomes over time.
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Coefficient of inbreeding (COI) measures an animal’s homozygosity or genetic “sameyness.” The higher the COI, the more homozygous or inbred an animal is. Conservation breeders typically consider a 10% average COI to be the ceiling for a healthy genetic population, while COIs exceeding 5% can begin to impact health. For context, an otherwise unrelated parent-child or sibling mating generates a COI ~25%, and The Kennel Club will not register puppies of such pairings save for rare circumstances.
The average Flat-coat COI is 33%, tripling the ceiling for a healthy population and exceeding the inbreeding of parent-child and sibling matings. The average COI has increased over time as more dogs are profiled, so the true number could be higher. It is unlikely that there exists a single Flat-coat with a COI within a healthy range.
It is important to note that COI calculated using pedigrees, rather than genetic data, is a useless metric in Flatcoats because even a 10-generation pedigree fails to incorporate the breed’s pronounced founder effect and genetic bottlenecks.
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A Flatcoat population analysis performed by Dr. Niels Pedersen at UC Davis instructs that there is little genetic variability among dogs within the breed, and the variation that does exist is evenly distributed, with no known pockets of unique genetics.
Dr. Evan’s, et al. estimated a scant 13% genetic variance across the Flatcoat population.
An analysis of Flatcoat genetic stratification among European and North American dogs found low allelic diversity and a tragically low fixation index of .03.
Whereas many breeds can turn to distinct populations in other regions or lineages to produce genetically diverse pairings, Flatcoat breeders enjoy no such luxury.This hopeless genetic profile is consistent with Flatcoat breed history, whereby a small handful of founder dogs established a breed that nearly went extinct during WWII. This also helps explain why high rates of inbreeding are universal across the breed when 5 and even 10-generation pedigrees suggest unrelatedness.
What the science says.
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Recent research confirms what basic genetics instructs - greater genetic diversity results in more favorable health outcomes and improved longevity.
A 2021 article by Bannasch, et al. compared health data with associated breed COIs and found COI to be significantly correlated with morbidity, with lower COI breeds enjoying overall better health and longevity than higher COI breeds. The article also highlights that inbreeding is not necessary for consistent breed type, as demonstrated by many low COI breeds.
The correlation of inbreeding and health outcomes seems especially salient where canine cancer is concerned. Pet health insurer, Nationwide, analyzed their claims database and found that Goldendoodles are 75% less likely to submit a cancer claim than either parent breed, and Labradoodles are 62% less likely. Overall, purebred dogs were twice as likely to submit a cancer claim than mixed breed dogs.
These are a small sampling of the many studies correlating genetic diversity and health outcomes. You can read more in our resources library.
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Advances in genomic mapping technology have provided researchers the tools to “prove” what basic genetics already instructs - inbreeding increases the risk that some alleles will “concentrate" while others will be lost.
In a closed gene pool, the totality of genetic material is finite and diminishes over time, consequent to both trait selection and genetic drift. The consequences of this process are most immediately apparent with Mendelian-inherited diseases, where a limited number of bad genes concentrate over generations. Many of these mutations become testable and predictable such that breeders can easily select away from them, just as they can avoid producing a coat color. Cancer and immune-mediated diseases, however, are more complicated.
We don’t know what most genes do, nor which alleles are favorable. And there exists a great deal of complex interplay among genes, and between genes and the environment. While the loss of any one allele can be good, bad, or neutral, the net effect of inbreeding is a concentration of some alleles at the expense of others and an overall reduction in genetic adaptability - like an investment portfolio overly committed to a small number of assets is more susceptible to market volatility, an inbred animal is more susceptible to pathogens and environmental influences.
While we may not know the full scope of genetic mechanisms influencing cancer, we know that an estimated 90% of UK Flatcoats and 70% of North American Flatcoats have genetics predisposing them to Histiocytic Sarcoma. We also know that Flat-coats have both high degress of homozygosity (~33%) and high rates of cancer (upwards of 70%) - a toxic soup of cancer genetics. And because the totality of the breed’s genetic ingredients have already been distributed across the gene pool, with a scant 13% genetic variance and .03% fixation index between North American and European Flatcoats, we can’t water down that soup or hope to re-introduce cancer-protector genes already lost to inbreeding. This also helps explain why longevity has declined over time despite careful breeding, and why we can’t select for longevity in a cancer-afflicted breed.
This article helps explain why genetic diversity is important even when we can’t ascertain the genes responsible for the disease, and this article explains why it’s especially relevant where cancer is concerned.
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Even supposing genetic marker tests were made available, Flatcoats’ extreme homozygosity and limited genetic variance hamper the usefulness of any such tests.
Given the cancer prevalence we know to exist within the breed - with upwards of 70% of Flatcoats dying from cancer and 70-90% of the population having at least some predisposing genetics - a significant percentage of the breed’s population would be implicated. Selecting against those cancer genetics would further bottleneck the breed’s already inbred population, risks amplifying other problems in the breed and further constricts depleted genetic resources.
Even with all the genetic tests and treatments at our disposal, we’d still have a highly inbred population with scant genetic variability, and an unsustainable closed gene pool.