Evaluation of quantitative trait loci for hip dysplasia in Labrador Retrievers.

Objective: To identify the quantitative trait loci (QTL) that contribute to hip dysplasia in dogs.

Animals: 192 Labrador Retrievers.

Procedures: Hip dysplasia was measured by use of the Norberg angle (NA), dorsolateral subluxation (DLS) score, and distraction index (DI).

Estimation of heritabilities, genetic correlations, and breeding values of four traits that collectively define hip dysplasia in dogs.

OBJECTIVE-To estimate heritabilities and genetic correlations among 4 traits of hip joints (distraction index [DI], dorsolateral subluxation [DLS] score, Norberg angle [NA], and extended-hip joint radiograph [EHR] score) and to derive the breeding values for these traits in dogs. ANIMALS-2,716 dogs of 17 breeds (1,551 dogs in which at least 1 hip joint trait was measured). PROCEDURES-The NA was measured, and an EHR score was assigned.

Transmission of relaxin and estrogens to suckling canine pups via milk and possible association with hip joint laxity.

Objective: To determine whether abnormal laxity of hip joints of canine pups with genetic predisposition to hip dysplasia (HD+) is related to ingestion of milk-borne hormones.

Animals: 7 female Labrador Retrievers with HD+ and 8 with low predisposition to hip dysplasia (HD-) and their offspring.

Procedures: Immunoactive relaxin, estrogen, and estrogen precursor concentrations in milk of HD+ lactating bitches and in serum of their pups were compared with those of HD- bitches and pups.

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.

Quantitative trait loci for hip dysplasia in a cross-breed canine pedigree.

Canine hip dysplasia is a common developmental inherited trait characterized by hip laxity, subluxation or incongruity of the femoral head and acetabulum in affected hips. The inheritance pattern is complex and the mutations contributing to trait expression are unknown. In the study reported here, 240 microsatellite markers distributed in 38 autosomes and the X chromosome were genotyped on 152 dogs from three generations of a crossbred pedigree based on trait-free Greyhound and dysplastic Labrador Retriever founders.

Evaluation of multiple radiographic predictors of cartilage lesions in the hip joints of eight-month-old dogs.

Objective: To determine the radiographic methods that best predict the development of osteoarthritis in the hip joints of a cohort of dogs with hip dysplasia and unaffected dogs.

Animals: 205 Labrador Retrievers, Greyhounds, and Labrador Retriever-Greyhound crossbred dogs.

Procedure: Pelvic radiography was performed when the dogs were 8 months old.

Effect of dorsal hip loading, sedation, and general anesthesia on the dorsolateral subluxation score in dogs.

Objective: To determine whether dorsal loading of the pelvis and type of chemical restraint affected the dorsolateral subluxation (DLS) score of dog hips. STYDY DESIGN: In vivo testing of diagnostic method.

Animals: Labrador retrievers, Greyhounds, and crosses between both breeds (n = 119 dogs).

Power of a Labrador Retriever-Greyhound pedigree for linkage analysis of hip dysplasia and osteoarthritis.

Objective: To estimate the number of dogs required to find linkage to heritable traits of hip dysplasia in dogs from an experimental pedigree.

Animals: 147 Labrador Retrievers, Greyhounds, and their crossbreed offspring.

Procedure: Labrador Retrievers with hip dysplasia were crossed with unaffected Greyhounds.

Quantitative genetics of traits associated with hip dysplasia in a canine pedigree constructed by mating dysplastic Labrador Retrievers with unaffected Greyhounds.

Objective: To determine the genetic influence on expression of traits associated with canine hip dysplasia.

Animals: 193 dogs from an experimental canine pedigree.

Procedure: An experimental canine pedigree was developed for linkage analysis of hip dysplasia by mating dysplastic Labrador Retrievers with nondysplastic Greyhounds.