THE FUTURE OF THE FIELD
Genetic disease testing can have a significant impact on improving canine health. These efforts will come from breeding to
decrease the prevalence of detrimental genetic mutations, the replacement of cumbersome and invasive testing methodologies,
and improved monitoring and treatment of clinical disease. Indeed, the testing of Irish setters by breeders for progressive
retinal atrophy resulted in a dramatic decrease in this disease in the United Kingdom in the span of only six years.16
Efforts to completely eliminate a mutation may reduce genetic diversity to the detriment of the breed, and, considering the
already severely limited gene pools of many breeds, caution must be taken. For example, veterinarians assisting breeders to
reduce disease incidence in their line may recommend breedings that are aimed at reducing the percentage of offspring homozygous
for recessive traits. The best method for diluting genetic disease and increasing genetic diversity is breeding outside of
the breed; however, many breed registries prohibit that with closed studbooks. Genetic registries are being created by various
organizations, including kennel clubs and breed organizations, through which animals can be certified free of certain genetic
mutations. Be aware that many registries require that specific laboratories perform the testing, and this requirement should
be taken into consideration at the outset in these cases.
Aside from assisting breeders, genetic testing is clinically relevant for diseases that are diagnosed either by exclusion,
such as degenerative myelopathy, or by invasive diagnostic tests, such as liver biopsy for copper toxicosis. Testing for the
MDR1 mutation responsible for the multi-drug sensitivity seen in many herding breeds would benefit the patient and the practitioner
as the list of problem drugs for these pets continues to grow.17 Genetic testing can also be used to help guide the monitoring and testing of at-risk patients. Owners of boxers, for instance,
may see greater value in routine cardiac monitoring if they know their pets are genetically at risk for heart disease. Veterinarians
can also assist clients searching for their next pet by understanding the genetic pedigrees made available by breeders, which
impacts the future health of those offspring.
Genetics is at the forefront of medicine for both people and animals, with interest in comparative medicine on the rise. The
One Health Initiative is a collaborative effort between the human medical community and veterinary organizations to combine
efforts to improve the lives of all species. In conjunction with the NHGRI at the National Institutes of Health, the NHGRI
Dog Genome Project is actively working to further knowledge of the canine genome by identifying genes responsible for breed
phenotypes such as chondrodysplasia as well as other genome mapping projects.
As the dog becomes increasingly valued for its unique genetic diversity, interest in it as a model for human genetic disease
will no doubt continue to increase with benefits for both species. The list of causative genes identified for canine disease
will continue to grow as will the list of genetic tests available to veterinarians, pet owners, and breeders. Personalized
medicine for the veterinary patient is right around the corner—if not already here—and you have the tools to provide that
level of care. The purebred canine community has the advantage of influencing the health of the next generation through careful
breeding. Through education and guidance from veterinarians, many of the mutations listed in Table 1 (PDF) could become increasingly less prevalent. Veterinarians knowledgeable in genetic testing can assist patients suffering from
genetic disease in receiving more accurate and timely diagnoses, which leads to the ultimate goal of better care.
ACKNOWLEDGEMENTS
The author would like to thank her mentor, Derry Roopenian, PhD, of the Jackson Laboratory, for his help and support, as well
as Anne Peaston, BVSc, DipVetClinStud, PhD, DACVIM (oncology), of the University of Adelaide, and Jill Recla of the Jackson
Laboratory for their valuable insights.
Caroline G. McPhee, DVM, PhD
The Jackson Laboratory
600 Main St.
Bar Harbor, ME 04609
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