Mankind has a way of taking something great and trying to make it greater.
Our belief, as a species, that we can improve on nature has gotten us into trouble over the years. The problem is that in our arrogance, we seem to get more than we bargain for.
Genetics are extremely complex and no single trait can be prioritized with selective breeding without the other traits that reside on the same gene coming along for the ride. 1
So when humans try to control how our dogs grow, look and act, we get some unwanted consequences. Almost every breed has its genetic watch list. From hip dysplasia to epilepsy, there are numerous disorders that have been shown to be heritable2. Mixed breed dogs can also carry genetic mutations, but these are strong breed predilections for many diseases and maladies.
There are so many genetic linked diseases in purebred dogs that I cannot list them all here, but those shopping for a purebred dog should certainly research the breed, as well as the breeder and his/her lines of dogs. Scientists that have done the work on some of these diseases have advised that not only should line breeding be avoided (which has been the advice to this point), but we should make a concerted effort to enlarge our breeding populations, rather than select for only those individuals that best meet the published breed standards.
Be mindful that current “designer breeds” like Doodles are techincally mixed breed, but since they came from pure bred ancestors, many will suffer from the diseases associated with BOTH of the genetic lines.
A purebred dog is statistically more likely to carry a genetic malformation that results in a disorder. Choosing dogs that meet a very strict standard for breeding has created a population bottleneck that has allowed undesirable traits to concentrate. Our current breeding standards need to be revised to help reduce the danger of further concentrating disease in our dogs.
As for those of us who are looking for a friend, your best bet for genetic health is selecting a mixed breed dog rescued from a shelter or saved from homelessness and make sure that you include your veterinarian in your decision. He or she has experience in dealing with breed associated disease and knows what to look for.
If you have questions about dog breeds, rescuing pets or designer dogs, please reach out to us!
Proc Natl Acad Sci U S A. 2015 Dec 22. pii: 201512501. [Epub ahead of print] Bottlenecks and selective sweeps during domestication have increased deleterious genetic variation in dogs Marsden CD1, Ortega-Del Vecchyo D2, O’Brien DP3, Taylor JF4, Ramirez O5, Vilà C6, Marques-Bonet T7, Schnabel RD8, Wayne RK1, Lohmueller KE9.
BMC Vet Res. 2015 Aug 28;11:175. doi: 10.1186/s12917-015-0463-0.International Veterinary Epilepsy Task Force’s current understanding of idiopathic epilepsy of genetic or suspected genetic origin in purebred dogs. Hülsmeyer VI1, Fischer A2, Mandigers PJ3, DeRisio L4, Berendt M5, Rusbridge C6,7, Bhatti SF8, Pakozdy A9, Patterson EE10, Platt S11, Packer RM12, Volk HA13.