Identification of quantitative trait loci for osteoarthritis of hip joints in dogs.

Objective: To identify quantitative trait loci (QTL) associated with osteoarthritis (OA) of hip joints of dogs by use of a whole-genome microsatellite scan.

Animals: 116 founder, backcross, F1, and F2 dogs from a crossbred pedigree.

Procedures: Necropsy scores and an optimized set of 342 microsatellite markers were used for interval mapping by means of a combined backcross and F2 design module from an online statistical program.

A random model for mapping imprinted quantitative trait loci in a structured pedigree: an implication for mapping canine hip dysplasia.

Genetic imprinting may have played a more notable role in shaping embryonic development of plants, animals, and humans than previously appreciated. Quantitative trait loci that are imprinted (iQTL) exert monoallelic effects, depending on the parent of origin, which is an exception to the laws of Mendelian genetics. In this article, we present a modified random effect-based mapping model to use in a genome-wide scan for the distribution of iQTL that contribute to genetic variance for a complex trait in a structured pedigree.

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.

Animals: 137 Labrador Retrievers, Greyhounds, and mixed-breed dogs.

Procedures: Necropsy scores ranging from 0 to 4 were obtained for each hip joint.

Modeling extent and distribution of zygotic disequilibrium: implications for a multigenerational canine pedigree.

Unlike gametic linkage disequilibrium defined for a random-mating population, zygotic disequilibrium describes the nonrandom association between different loci in a nonequilibrium population that deviates from Hardy-Weinberg equilibrium. Zygotic disequilibrium specifies five different types of disequilibria simultaneously that are (1) Hardy-Weinberg disequilibria at each locus, (2) gametic disequilibrium (including two alleles in the same gamete, each from a different locus), (3) nongametic disequilibrium (including two alleles in different gametes, each from a different locus), (4) trigenic disequilibrium (including a zygote at one locus and an allele at the other), and (5) quadrigenic disequilibrium (including two zygotes each from a different locus). However, because of the uncertainty on the phase of the double heterozygote, gametic and nongametic disequilibria need to be combined into a composite digenic disequilibrium and further define a composite quadrigenic disequilibrium together with the quadrigenic disequilibrium.

Assessment of bone mineral density of the femoral head in dogs with early osteoarthritis.

Objective: To compare the bone mineral density (BMD) of the proximal portion of the femur in dogs with and without early osteoarthritis secondary to hip dysplasia.

Animals: 24 dogs (3 Greyhounds, 6 Labrador-Greyhound crossbreeds, and 15 Labrador Retrievers).

Procedure: Computed tomography (CT) of the pelvis, including a bone-density phantom, was performed for each dog.