The Genetics of Hip Dysplasia in Labrador Retrievers & German Shepherd Dogs

Research Aim: To identify regions of the genome that contribute to Hip Dysplasia (HD) in Labrador Retrievers and German Shepherds.

Canine Hip Dysplasia is a debilitating and costly disease that plaguesmany breeds. Recent evidence indicates that susceptibility is strongly genetic, but that environmental factors modify severity. A landmark study by Purina demonstrated that genetic susceptibility is exacerbated by rapid weight gainduring puppyhood. Diligent breeders and owners have reduced severity bymaintaining lean diets in their dogs. However, this has had an unforeseen consequence — controlling environmental inﬂuences has unfortunatelymasked the causative genes, thereby making selective breeding for healthyhip conformation more difﬁcult.

Resolving Complex Diseases in Dogs: Recent advances in canine genetics have created entirely new opportunities to resolve complex traits and diseases. The conventional strengths of canine genetics (large sibships and multiple generations availablefor DNA sampling) are matched by some powerful, yet lesser known beneﬁts. The structure of breed populations lends support to assumptions about gene sharing by common descent, such that two GermansShepherds with HD will almost certainly have the same genetic causes (this is seldom true of medicalgenetics in diverse human populations). Breeders are in a position to ascertain a large number of DNAsfrom their bloodline, and this can confer enormous power to genetic studies.

The Dog Genome: The inherent strengths of dog genetics are being matched by unprecedented tools forresearch. The complete DNA sequence of the dog genome has been deciphered — all 2.4 billion letters of the code are now known. This resource is a complete compendium of canine genes — all 20,000 — as wellas their precise location. The code has directly yielded an enormous set of DNA markers that optimize exploration of the genetic landscape. Whereas parentage tests rely on roughly a dozen markers, newtechnologies provide a readout on 125,000 markers (a 10,000-fold increase in informativeness!).

Improving Experimental Design with Genealogy: Researchers at UC Davis, Johns Hopkins, and theUniversity of Chicago are developing novel methods of gene mapping that exploit the most unique resourcein dog genetics — whole breed genealogies. Because the ancestry of purebred dogs is fully known (andusually embedded in a digitized pedigree database), statisticians can identify the most powerful individualdogs for ﬁrst-phase mapping. The approach has a modest beneﬁt for mapping simple traits in familialpedigrees, but it has a pronounced effect on improving the chances for successfully resolving complex diseases using population-based samples (mostly unrelated dogs).

Improving Health & Performance by Resolving HD: The emergence of new resources (the dog genome sequence), newtechnologies (high density gene mapping chips), and newmethodologies (selective sampling via genealogy) make HDgenetically tractable. Geneticists at the Veterinary Genetics Laboratory at the UC Davis School of Veterinary Medicine invite clinical experts and breeders to help us develop the necessary DNAbank from Labrador Retrievers and German Shepherds severelyafﬂicted with HD. Multiple samples from individual bloodlines are of particular interest, though any DNA from an affected dog is being sought. Blood samples(with accompanying registration numbers) afford high density DNA typing. All costs will be reimbursed; a Federal Express account number will be provided for shipping.

For Information: Contact Alison Ruhe at (530) 754-8765 or at Alison@ucdavis.edu

UC Davis School of Veterinary Medicine seeks help from HandicappedPets.com to cure Hip Dysplasia

The Genetics of Hip Dysplasia in Labrador Retrievers & German Shepherd Dogs