Guidelines for breeding
Owners with dogs testing as Carriers (A/N), or At-Risk (A/A) are strongly encouraged to share these results with their attending
veterinarian and seek genetic counseling when making breeding decisions. The "A" (mutated) allele appears to be very common
in some breeds. In these breeds, an overly aggressive breeding program to eliminate dogs testing A/A or A/N might be devastating
to the breed as a whole because it would eliminate a large fraction of the high quality dogs that would otherwise contribute
desirable qualities to the breed. Nonetheless, DM should be taken seriously. It is a fatal disease with devastating consequences
for the dog, and can be a trying experience for the owners that care for them. A realistic approach when considering which
dogs to select for breeding would be to treat the test results as one would treat any other undesirable trait or fault. Dogs
testing At-Risk (A/A) should be considered to have a more serious fault than those testing as Carriers (A/N). Incorporating
this information into their selection criteria, breeders can then proceed as conscientious breeders have always done: make
their breeding selections based on all the dog's strengths and all the dog's faults. Using this approach and factoring the
DM test results into the breeding decisions should reduce the prevalence of DM in the subsequent generations while continuing
to maintain and improve upon positive, sought after traits.
The allelic frequency may be as high as 75% in breeds prone to DM. (unpublished data, Dr. Gary S. Johnson – Animal Molecular
Genetics Laboratory, University of Missouri). We recommend that breeders take into consideration the DM test results as they
plan their breeding programs; however, they should not over-emphasize the test results. Instead, the test result should be
one factor among many in a balanced breeding program.
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