Dachshund Genetic Diversity in 2015
The Kennel Club has published the results of a major research study which used their pedigree database to investigate the genetic diversity of UK-registered pedigree dogs. The study examined pedigrees of dogs registered between 1980 and 2014.
This report is a summary of the results presented for the six varieties of Dachshund. For simplicity of presentation, data has been rounded.
Terminology
There are some key terms which readers need to understand in relation to the KC paper.
Inbreeding
This is the mating of related individuals and, in a closed population, such as pedigree dogs, is inevitable to some extent. It is increased when breeders use selection for particular traits, or when a small number of stud dogs are used regularly.
Coefficient of Inbreeding (COI)
This is a measure of risk. It identifies the probability that two genes, inherited from each parent are identical by descent. The more inbred a dog (or population) the higher will be the COI value and the more likely that two harmful genes will come together to produce puppies with inherited defects. With many imported dogs the KC only has 3 generation pedigrees and this is likely to result in COI calculations which underestimate the true degree of inbreeding and common ancestors.
Effective Population Size (EPS)
This is the number of breeding animals in an idealised, hypothetical population that
would be expected to show the same rate of loss of genetic diversity (rate of inbreeding) as the breed in question. It may be thought of as the size of the ‘gene pool’ of the breed. The lower the EPS, the more vulnerable the breed is because of its reduced genetic diversity. An effective population size of below 50 (inbreeding rate of 1.0% per generation) indicates the future of the breed many be considered to be at risk.
There is no correlation between the number of dogs registered and a breed's EPS; numerically strong breeds can have low EPS values and breeds with relatively few registrations can have higher EPS values.
Smooth-haired Dachshunds
The breed has seen a reduction in registrations almost continuously since 1980. The trend reported by the KC is 5 fewer dogs registered per year on average. While this might not seem like many, cumulatively, over 25 years annual registrations have dropped from over 350 to around 150.
It appears that the extensive use of popular dogs as sires which was evident in the 80s and 90s has eased a little in the past five years.
Long-haired Dachshunds
The breed has seen a reduction in registrations almost continuously since 1980. The trend reported by the KC is 10 fewer dogs registered per year on average. While this might not seem like many, cumulatively, over 25 years annual registrations have dropped from over 500 to less than 150.
Generation interval: the average age (in years) of parents at the birth of offspring which themselves go on to reproduce is 4.
Inbreeding coefficients increased to around 10% by 2000 and have remained around that level ever since. Given that the population has been declining, it is encouraging to note that COI levels have not increased at the same time.
The estimated effective population size is 59.
Generation interval: the average age (in years) of parents at the birth of offspring which themselves go on to reproduce is 4.
Inbreeding coefficients increased steadily to around 14% by 2000 and have remained around that level ever since. Given that the population has been declining, it is a concern to note that COI levels have not decreased in recent years.
The estimated effective population size is 40, which is well below the 50 level that many geneticists consider to put a population at risk.
It appears that the extensive use of popular dogs as sires which was evident in the 90s has eased a little but this still has to be a point of concern for the breed, given its declining popularity.
Wire-haired Dachshunds
The breed has seen an increase in registrations almost continuously since 1980. The trend reported by the KC is 5 more dogs registered per year on average. While this might not seem like many, cumulatively, over 25 years annual registrations have risen from around 150 to 350.
Generation interval: the average age (in years) of parents at the birth of offspring which themselves go on to reproduce is 4.
Inbreeding coefficients increased steadily to around 12% by 1995 and have steadily reduced to around 6% now. The breed has seen numerous imports over that period with US, European and Scandinavian bloodlines being added to the gene pool.
The estimated effective population size is 298, which is well above all the other Dachshund varieties.
There appears to be extensive use of popular dogs as sires in this breed and that has been a consistent feature since the mid-80s.
This may also be a reflection of the relatively large number of imported males which have been widely used at stud. We do therefore need to be cautious when interpreting the data on COI as the KC pedigrees of these dogs often only cover three generations. This would result in a lower COI value than would be calculated from a more extended pedigree.
Miniature Smooth-haired Dachshunds
The breed has seen an increase in registrations almost continuously since 2001. The trend reported by the KC is 65 more dogs registered per year on average. This is an average for the 35 years reported and underestimates the rate of increase since 2001. Over the last 15 years annual registrations have increased from about 1100 to around 3000 which is an average increase of nearly 160 p.a.
Generation interval: the average age (in years) of parents at the birth of offspring which themselves go on to reproduce is 3. This means Mini Smooths are typically having litters a year younger than the three Standard varieties.
Inbreeding coefficients increased to around 11% by 2001 but have declined steadily to around 7.5% now.
The estimated effective population size is 98.
It appears that the extensive use of popular dogs as sires has increased, particularly in the past 10 years. The most used stud dogs produced 2-3 times as many puppies as any of the Standard variety studs.
Miniature Long-haired Dachshunds
The breed has seen a reduction in registrations almost continuously since 1995. The trend reported by the KC is 21 fewer dogs registered per year on average. While this might not seem like many, cumulatively, over 25 years annual registrations have dropped from over 2000 to less than 800.
Generation interval: the average age (in years) of parents at the birth of offspring which themselves go on to reproduce is 4.
Inbreeding coefficients increased steadily to around 8% by 2000 and have remained between 7% and 8% ever since. Given that the population has been declining, it will be important that COI values do not increase, although this is likely to be difficult.
The estimated effective population size is 90, which is close to a sustainable level.
There appears to be extensive use of popular dogs as sires in this breed, albeit not at the level seen in Mini Smooths. In a breed with declining registrations, this could be a point of concern for breeders.
Miniature Wire-haired Dachshunds
The breed has seen registrations fluctuate between 600 and 900 since the early 80s, although there has been a decline in popularity from a peak in 2008 to today. This may be attributable to concerns over the presence of Lafora Disease in the breed. Hopefully, now there is a reliable DNA test available, puppy buyers will able to be more confident about choosing this variety of Dachshund. The trend reported by the KC is 8 more dogs registered per year on average over the 25 year period.
Generation interval: the average age (in years) of parents at the birth of offspring which themselves go on to reproduce is 3.
Inbreeding coefficients increased steadily to around 13% by 2000 and have reduced to around 8% now, although they were relatively steady around 11% until 2012. The breed has seen several imports over that period with Scandinavian bloodlines, in particular, being added to the gene pool. As with Wires, for many imported dogs the KC only has 3 generation pedigrees and this is likely to result in COI calculations which underestimate the true degree of inbreeding.
The estimated effective population size is 110, which could be considered to be a relatively safe level in order to maintain a viable population.
There appears to be extensive use of popular dogs as sires in this breed and that has been a consistent feature since the mid-80s.
Summary
Colour-coding in the Summary Table:
Registrations: Red = declining, Amber = broadly static, Green = increasing
COI: Red = >12.5%, Amber = 6.25-12.5%, Green = < 6.25%
EPS: Red = <50, Amber = 51-100, Green = >100
Popular Sires: Red = “extensive use”, Amber = “some reduction in use” (taken from the KC report
Declining registrations and low Effective Population Sizes are points of concern for the Smooth and Long-haired varieties. High average COI levels are also a point of concern for Longs.
Declining registrations and the overall trend in COI when taken with extensive use of “popular sires” are points of concern for the Miniature Long-haired variety.
While low levels of inbreeding and a high EPS in Wires are positive features from this analysis, a point of concern is the extensive use of popular sires which could have a longer-term detrimental effect on genetic diversity.
It remains to be seen whether the decline in registrations of Mini Wires which began in 2008 will continue now that a Lafora DNA test is available. Points of concern are the moderately high average COI levels and the extensive use of popular sires.
Further information
Note: The graphs are from the KC’s reports on each breed. The vertical axis scale is not the same on each graph and they don’t necessarily start at zero.
A peer-reviewed paper outlining general trends and points of interest is available from the online journal Canine Genetics and Epidemiology (http://www.cgejournal.org/) and reports for the 6 Dachshund varieties are featured on the Kennel Club website as well as a Q&A document and infographics http://www.thekennelclub.org.uk/vets-researchers/publications,-statistics-and-health-results/breed-population-analyses