Linebreeding practices expedite the appearance of recessive diseases
in purebred dog populations.
The present study identified specific breed groupings that contributed to disorders being more frequently observed
in the purebred dog population.
Not exact matches
Disorders with equal prevalence
in purebreds or mixed breeds seemed to be more ancient mutations that are widely spread through the
dog population
In contrast, disorders that occurred equally among
purebred and mixed - breed
dogs appeared to represent ancient gene mutations that had become widely spread throughout the
dog population.
Purebred dogs were more likely to remain
in their homes, leaving shelter
populations that are 75 - 80 percent mixed breeds.
A study by UC Davis showed that there was a prevalence of genetic disorders
in both
populations (rescue and bred): «Recently derived breeds or those from similar lineages appeared to be more susceptible to certain disorders that affect all closely related
purebred dogs, whereas disorders with equal prevalence
in the two
populations suggested that those disorders represented more ancient mutations that are widely spread through the
dog population.»
Strader established National Mill
Dog Rescue
in 2007 after learning about a large - scale breeding operation, or «puppy mill,»
in Missouri that was closing down and auctioning off its
purebred population.
In the same way that inbreeding among human
populations can increase the frequency of normally rare genes that cause diseases, the selective breeding that created the hundreds of modern
dog breeds has put
purebred dogs at risk for a large number of health problems, affecting both body and behavior.
It is seen
in both
purebred and mix - breed
dogs, but some breeds, like the Aussie, have a much higher incidence than is seen
in dogs as a whole, due to the restricted gene pool typical of any
purebred population.
Purebred dogs were more likely to remain
in their homes, leaving shelter
populations at 75 - 80 percent mixed breeds.
While some purpose - bred guide, service, or ranch
dogs may be immune to infertility disease as a result of less exposure to the general
population, the crashing fertility rate
in quality
purebreds can not be ignored.
The loss of genetic diversity
in purebred dogs can be attributed to two major
population bottleneck events: the first occurring during domestication; and the second arising from breed formation where the repeated use of popular sires, line breeding, breeding for specific phenotypic traits, and promotion of the breed barrier rule, contributed to overall loss
in genetic variation [15 - 19].
If we disqualified all of the
dogs with the slightest elbow issue, we would lose 31 % of the breeding
population in every generation, compounding a genepool problem that is historically present
in purebred dogs, and far more dangerous to the
dogs than any heritable disease.
The proportion of mixed - breed and subclassifications of
purebred dogs for each of those conditions was determined to distinguish what specific backgrounds may contribute to the inherited conditions seen with higher prevalence
in the
purebred population or if
in fact,
purebreds as a whole were more at risk than the mixed - breed
dogs.
For each disorder, healthy controls seen at the hospital during that same time period were matched for age, weight, and sex to each affected
dog to determine risk of disease presentation
in the
purebred group as compared to that of the mixed - breed
population.
The present study illustrated that certain subpopulations of the
purebred dog population were more likely to display certain conditions while other subpopulations were not statistically different than mixed - breed
dogs in terms of disease prevalence.
This study suggests that subpopulations of the
purebred dog population are more likely to exhibit certain inherited conditions while other subpopulations do not differ statistically from mixed - breed
dogs in terms of how common these diseases are.
Such a bias would inflate the prevalence of conditions
in the study's
purebred dog population.
We recently have reported that for 13 inherited disorders, there were no statistically detectable differences
in risk of disease presentation between the
purebred and mixed - breed
dog populations and one condition was more prevalent
in mixed - breeds [6].
For some disorders, such as hypothyroidism,
purebred dogs may be more likely diagnosed with the condition due to pre-breeding health screens that are rarely done
in the mixed - breed
population.
In comparing the purebred dog population to the mixed - breed dog population for ten inherited conditions found at a higher frequency in purebred dogs, the current data indicate that risk for certain inherited disorders can be apportioned to specific purebred population
In comparing the
purebred dog population to the mixed - breed
dog population for ten inherited conditions found at a higher frequency
in purebred dogs, the current data indicate that risk for certain inherited disorders can be apportioned to specific purebred population
in purebred dogs, the current data indicate that risk for certain inherited disorders can be apportioned to specific
purebred populations.
For aortic stenosis, GDV, early onset cataracts, dilated cardiomyopathy, elbow dysplasia, epilepsy, and portosystemic shunt, most
purebred groups were not statistically distinct from the mixed - breed
population with higher prevalence
in purebreds restricted to distinct subsets of
purebred dogs.
For ten other inherited conditions, the
purebred dog population had greater prevalence than that seen
in mixed - breeds: aortic stenosis, atopy / allergic dermatitis, gastric dilatation volvulus (GDV), early onset cataracts, dilated cardiomyopathy, elbow dysplasia, epilepsy, hypothyroidism, intervertebral disk disease (IVDD), and portosystemic shunt.