The Doberman Heart
An estimated 60% of Dobermans will be diagnosed with Dilated Cardiomyopathy (DCM), which is a fatal disease. DCM has an average age of onset of 6-8 years old, but can develop at any age. There is no definitive test to determine if a dog will develop this disease in the future. DCM incidence in a dog's pedigree, along with confirmation that neither parent is already affected, are the far and away the best two tools we have to help us minimize the risk of producing puppies that might become affected by this condition. Every ethical breeder should have a recent, clear ECHOCARDIOGRAM and 24 HR HOLTER MONITOR done on their breeding pair. See the different sections below to learn more about DCM, the tests used to screen for it, how genetics play a roll, and how we incorporate this information into our breeding program. While genetic testing is a valuable tool, No ethical breeder will call their dogs "cardio clear" based on DCM1/2 gene test results.
What is DCM?
Most Doberman DCM exhibits as left-sided heart failure. However, about 30% of cases exhibit arrhythmias which can result in sudden death. Early signs of the disease are subtle (gradual exercise intolerance and weight loss) and are very frequently overlooked or attributed to other causes. By the time a Doberman is overtly symptomatic (lethargic, coughing) the disease has already progressed to end stage and life expectancy even with medical intervention is short: days to weeks. However, if preclinical signs of DCM are found and supportive medication and monitoring are begun while the disease is still in the occult phase, affected dogs can expect many more months and even years of life before end stage DCM presents.
Tests for DCM
Because DCM can initially present in two different ways, via structural changes to the heart or via ventricular arrhythmias, it is important to screen for both. An echocardiogram directly measures heart morphology, and a 24-hour ambulatory electrocardiograph (Holter) checks for the presence of arrhythmias. It is recommended that every Doberman have both screenings done at least yearly starting at the age of two because by the time a dog shows overt symptoms, they have already sustained irreversible damage to the heart and their long-term prognosis is poor.
DCM Genetics
Studies by Dr. Meurs, a veterinary cardiologist at North Carolina State University, found two potential genetic mutations that were initially believed to be strongly linked to a given dog's risk of developing the disease. Unfortunately, follow up studies have found that these two mutations are not the answer that Dr. Meurs had hoped for. Many dogs with copies of both mutations have healthy cardiac checkups their entire lives and pass away due to other causes at well past 10 years old. Additionally, quite a few dogs who have testing clear for both mutations have gone on the develop and die from the disease. The reality is that DCM is likely due to a very complex interrelation of both cardio-protective and cardio-destructive genetic mutations, and that DCM1 (PDK4) and DCM2 (TTN) gene test results do not accurately predict DCM risk at this time. No ethical breeder will call their dogs "cardio clear" based on DCM1/2 gene test results.
(1) Assessment of PDK4 and TTN Gene Variants in 48 Doberman Pinschers with Dilated Cardiomyopathy. Kathryn M. Meurs, DVM, PhD, Joshua Stern, DVM, PhD, Darcy Adin, DVM, Bruce W. Keene, DVM, MS, Theresa C. De Francesco, DVM, and Sandra P. Tou, DVM. Journal of the American Veterinary Medical Association. (November 15, 2020, Vol. 257, No. 10, Pages 1041-1044)
(2) Canine Dilated Cardiomyopathy - Recognition & Clinical Management. Kathryn M. Meurs, DVM, PhD. (2002).Waltham/OSU Symposium
(2) Canine Dilated Cardiomyopathy - Recognition & Clinical Management. Kathryn M. Meurs, DVM, PhD. (2002).Waltham/OSU Symposium
Genetic Diversity
Inbreeding depression is a term describing the negative effects high levels of inbreeding can have on a population of animals. One such effect is reduced longevity: a recent study found a direct relationship between increased inbreeding coefficient and decreased lifespan. The Coefficient of Inbreeding (COI) is a measurement assessing inbreeding in an individual. COI ranges from completely diverse/outbred at 0%, to completely inbred at 100%. As a reference, a sibling-to-sibling mating in a healthy, diverse population would produce a progeny with an approximately 25% COI.
Unfortunately, Dobermans are critically inbred on a breed wide level, with an average COI of 40%. Additionally, no registered purebred Doberman in the 3,000+ dogs tested through the Doberman Diversity Project have been found to have a COI lower than 20%.
Unfortunately, Dobermans are critically inbred on a breed wide level, with an average COI of 40%. Additionally, no registered purebred Doberman in the 3,000+ dogs tested through the Doberman Diversity Project have been found to have a COI lower than 20%.
How to lower COI Through Breeding
If the breed is highly inbred, how can you lower inbreeding? While overall the breed is highly interrelated, individual Dobermans cluster into population subsets that are more highly related to each other than to Dobermans of other clusters. Breeding across these subsets, while also keeping a close eye on overall pedigree health and longevity in any potential stud dog, will produce puppies with much lower COIs.
There are two distinct population subsets in Dobermans where pedigree health and longevity is consistently tracked and considered: American show lines, and European working lines. Crossing American show lines and European working lines is one way Kickturn helps give the next generation of Dobermans the best chance for a long and healthy life. Additionally, we feel that such a breeding brings an excellent balance between form and function.
There are two distinct population subsets in Dobermans where pedigree health and longevity is consistently tracked and considered: American show lines, and European working lines. Crossing American show lines and European working lines is one way Kickturn helps give the next generation of Dobermans the best chance for a long and healthy life. Additionally, we feel that such a breeding brings an excellent balance between form and function.
Individual COI vs Breedwide Diversity
In addition to the inbreeding of an individual dog, there is also the diversity of the entire breed's gene pool to consider. Unfortunately, the Doberman gene pool's diversity is as limited as it is inbred: most well-bred Dobermans are very closely related to each other. There are, however, a few lines found in some lesser-known populations that are relatively unique. We don't know yet whether these rare genetics are helpful (lines that escaped the genetic bottlenecks of the breed's history) or harmful (breeders may have incidentally bred away from these genes because of prior issues). But we do know from recent research that the less bottle-necked a breed's gene pool is, the better the breed's overall health and longevity.
Because the Doberman gene pool is so limited, healthy dogs that have uncommon genetics should be bred to limit further loss of genetic diversity on a breed level. This is not a focus of the Kickturn breeding program because our foundation bitch does not have many of these rare genetics, but we follow with interest and support those who focus on preserving the genetics of the breed as a whole. Please see the Measuring COI and Diversity section below for more information.
Because the Doberman gene pool is so limited, healthy dogs that have uncommon genetics should be bred to limit further loss of genetic diversity on a breed level. This is not a focus of the Kickturn breeding program because our foundation bitch does not have many of these rare genetics, but we follow with interest and support those who focus on preserving the genetics of the breed as a whole. Please see the Measuring COI and Diversity section below for more information.
Measuring COI & Diversity
As part of our commitment to health, we genetically tested our foundation bitch, as well as every Kickturn puppy through both Embark and UC Davis. There is a lot of discussion in the breed world about these two tests. Below is a bit of information about them both.
There are different statistical methods to measure an individual dog's COI. True distribution of genetics can vary greatly from pedigree-based COI calculations that assume ideal averages of inheritance. Currently the most specific approach to measuring COI in dogs (other than direct calculation from full genome sequencing, which is not yet commercially available) is a method based on measuring "runs of homozygosity", or tracks of identical genetic markers that indicate inbreeding in the dog's pedigree. Embark's genome wide SNP marker panel uses this method to calculate COI, which you can read more about on their site.
Another statistical method to measure a population's diversity is through the use of population-specific STR markers. UC Davis Veterinary Genetics Lab (VGL) uses these markers to mathematically model how an individual relates to population as a whole with a value called the dog's Outlier Index or (OI). They also use these STR markers to create their own measure of how inbred a dog is (analogous to COI), called Internal Relatedness (IR). They feel this indicates how inbred or unique a dog is relative to the rest of its own breed, rather than as a strict measure of inbreeding. More information about how the UC Davis Veterinary Genetics Lab developed the Canine Genetic Diversity test based on STR marker data for Dobermans here.
While we appreciate the value of using VGL's measure of OI to directly compare individual dogs to the breed as a whole for purposes of preserving what is left of genetic diversity, we feel that inbreeding is best measured in absolute values using a genome wide panel such as Embark's because it considers a much larger portion of the dog's genome in its calculations than the specific markers used by VGL. Thus, we ultimately use the Embark panel to guide our efforts to reduce the level of inbreeding in the puppies we produce. Our primary purpose in continuing to test with UC Davis VGL is to stay aware of how our dogs relate to the breed population as a whole.
There are different statistical methods to measure an individual dog's COI. True distribution of genetics can vary greatly from pedigree-based COI calculations that assume ideal averages of inheritance. Currently the most specific approach to measuring COI in dogs (other than direct calculation from full genome sequencing, which is not yet commercially available) is a method based on measuring "runs of homozygosity", or tracks of identical genetic markers that indicate inbreeding in the dog's pedigree. Embark's genome wide SNP marker panel uses this method to calculate COI, which you can read more about on their site.
Another statistical method to measure a population's diversity is through the use of population-specific STR markers. UC Davis Veterinary Genetics Lab (VGL) uses these markers to mathematically model how an individual relates to population as a whole with a value called the dog's Outlier Index or (OI). They also use these STR markers to create their own measure of how inbred a dog is (analogous to COI), called Internal Relatedness (IR). They feel this indicates how inbred or unique a dog is relative to the rest of its own breed, rather than as a strict measure of inbreeding. More information about how the UC Davis Veterinary Genetics Lab developed the Canine Genetic Diversity test based on STR marker data for Dobermans here.
While we appreciate the value of using VGL's measure of OI to directly compare individual dogs to the breed as a whole for purposes of preserving what is left of genetic diversity, we feel that inbreeding is best measured in absolute values using a genome wide panel such as Embark's because it considers a much larger portion of the dog's genome in its calculations than the specific markers used by VGL. Thus, we ultimately use the Embark panel to guide our efforts to reduce the level of inbreeding in the puppies we produce. Our primary purpose in continuing to test with UC Davis VGL is to stay aware of how our dogs relate to the breed population as a whole.
The Doberman Diversity Project
The Doberman Diversity Project partners with Embark in order to access participant's raw genomic data. This vast dataset is a priceless resource for researchers trying to help the breed's health. We submit all of our dogs and puppies' Embark test results as well as updated health test results, to the Doberman Diversity Project in support of their mission.
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Other Health Testing
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In addition to cardiac health and genetic diversity, it is important for breeders to test for other potential issues in the breeding pair. Dobermans are prone to and should be tested for:
The OFA is a public database for health test results. Completion and recording of all breed club recommended health testing with the OFA will earn a dog its CHIC certification. Piper was CHIC certified before she was bred and is retested annually to keep her certification current. We believe transparency is an important part of responsible breeding and update our dogs' Dobquest Profiles with all of their test results regularly. We also request that puppy homes keep us appraised of any health issues so that we can have a full picture of the health of our lines. |
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