Quantitative genetics of secondary hip joint osteoarthritis in a Labrador Retriever-Greyhound pedigree.
OBJECTIVE
To evaluate the quantitative inheritance of secondary hip joint osteoarthritis in a canine pedigree.


METHODS
137 Labrador Retrievers, Greyhounds, and mixed-breed dogs.


METHODS
Necropsy scores ranging from 0 to 4 were obtained for each hip joint. Seven unaffected Greyhounds with normal hip joint conformation were also used for genetic modeling, but were not euthanized. Sixty-six male and 71 female dogs were allocated to 2 groups (< or = 12 months of age and > 12 months of age). Statistical models were developed to establish the inheritance pattern of hip joint osteoarthritis that developed secondary to hip dysplasia.


RESULTS
62 dogs had evidence of osteoarthritis in a hip joint, and 75 had no evidence of osteoarthritis. After sex was adjusted for, the necropsy score was found to be inherited additively but without dominance. Each Labrador Retriever allele increased the necropsy score by 0.7 to 0.9 points, compared with the Greyhound allele, and male sex increased the necropsy score 0.74 over female sex. Approximately 10% of the variation in necropsy score was attributable to the litter of puppies' origin.


CONCLUSIONS
Because secondary hip joint osteoarthritis is inherited additively, selection pressure could be applied to reduce its incidence. Similar statistical models can be used in linkage and association mapping to detect the genes in the underlying quantitative trait loci that contribute to hip joint osteoarthritis.
Hays
Laurel
L
Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
Zhang
Zhiwu
Z
Mateescu
Raluca G
RG
Lust
George
G
Burton-Wurster
Nancy I
NI
Todhunter
Rory J
RJ
D000367:Age Factors; D000818:Animals; D003433:Crosses, Genetic; D004285:Dogs; D005260:Female; D008040:Genetic Linkage; D005838:Genotype; D006619:Hip Dysplasia, Canine / Q000235:genetics*; D008297:Male; D008957:Models, Genetic; D015207:Osteoarthritis, Hip / Q000235:genetics* / Q000662:veterinary*; D010375:Pedigree; D040641:Quantitative Trait Loci; D012737:Sex Factors