Role of the Orthopedic Foundation for Animals in the control of canine hip dysplasia.

The objectives of the Dysplasia Control Registry, the procedure for submitting radiographs, and the radiographic evaluation process are described. The results from the radiographic evaluation of 321,183 dogs are reported by hip phenotypic ratings and breed frequency of canine hip dysplasia. Breeds at risk are documented. Comparison of dogs born between 1981 and 1988 with those born between 1972 and 1980 demonstrated that the frequency of canine hip dysplasia was reduced in 79% of breeds, and the frequency of excellent hips was increased in 88% of the breeds. Reliability of preliminary hip evaluations of dogs under 24 months of age is reported to vary by breed, and the results of 9,161 preliminary evaluations are documented.     

How the Orthopedic Foundation for Animals (OFA) is tackling inherited disorders in the USA: using hip and elbow dysplasia as examples

The Orthopedic Foundation for Animals (OFA) maintains an on-line health pedigree database for inherited disorders of animals. With the American Kennel Club Canine Health Foundation, the OFA maintains the Canine Health Information Center (CHIC) for parent breed clubs to identify breed-specific required health tests. Analysis of the results of OFA evaluations in the hip and elbow registries show that selection based on phenotype improves conformation. Disorders with complex inheritance respond best to selection based on depth (ancestors) and breadth (siblings) of pedigree health test results. This information can be derived from vertical pedigrees generated on the OFA website.     

Observations on the technical quality of radiographs submitted to a veterinary college.

The technical quality of 75 sets of radiographs submitted from general practice was assessed. The most serious faults were underdevelopment and failure to collimate the beam adequately. The correction of these two faults should significantly improve the overall standard of veterinary practice radiography.     

Canine hip dysplasia radiographic screening. Prevalence of rotation of the pelvis along its length axis in 7,012 conventional hip extended radiographs.

The prevalence of rotation of the pelvis along its length axis was noted, as was the number of rotations towards the right or left hand side of the dog, on 7,012 conventional hip extended radiographs, which were sent for official screening. 29.8% of the radiographs showed a rotation the pelvis. The rotation was statistically more frequent towards the left hand side of the dog. The number of rejected radiographs for too important pelvis rotation was only 5.2%. The consequences of the pelvis rotation on the Norberg-Olsson angle, on the dorsal femoral head coverage, and in the aspect of cranial acetabular edge have to be taken into account when scoring the dog for hip dysplasia.     

Orthogonal view analysis for evaluating the femoral component position of total hip implants in dogs using postoperative radiographs

OBJECTIVE: To show the ability to obtain repeatable, accurate, quantitative data to assess the position of the femoral component of canine total hip implants using postoperative radiographs. STUDY DESIGN: Cadaveric study and clinical trial. ANIMALS: Five cadaveric canine femurs and 4 patients. METHODS: Femoral implants were placed into 5 cadaveric canine femurs in predetermined locations. Orthogonal radiographs were taken of each femur at 10 degrees intervals as they were moved through a natural range of hip motion. An assessment of implant position was made with each set of radiographs and analyzed to observe significant inconsistencies in the values obtained when the femur was repositioned. Three investigators positioned and radiographed the hips of 4 client-owned dogs that had total hip arthroplasty (THA). Each investigator obtained a set of orthogonal radiographic views from which implant position was measured. The measurements obtained from each investigator's set of radiographs were statistically analyzed to evaluate for interobserver differences. RESULTS: The methods described indicate that consistent data regarding femoral implant placement can be obtained from postoperative radiographs of THA patients. Under most circumstances, change in position of the femur did not significantly affect femoral implant measurements. There were no significant differences noted among values obtained by different investigators. CONCLUSIONS: Measurements based on the femoral and implant axes obtained from orthogonal radiographic views of the femur provide a means for obtaining accurate and consistent quantitative data regarding femoral implant position using postoperative radiographs of canine THA patients. CLINICAL RELEVANCE: Acquisition of quantitative information about femoral implant position using postoperative radiographs will facilitate development of a readily available data source. This information, attainable in a clinical setting, may help identify elements of implant position that are important in determining the clinical outcome of THA in 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. Age at detection of femoral capital ossification, distraction index (DI), hip joint dorsolateral subluxation (DLS) score, and hip joint osteoarthritis (OA) were recorded. Power to find linkage of a single marker to a quantitative trait locus (QTL) controlling 100% of the variation in a dysplastic trait in the backcross dogs was determined. RESULTS: For the DI at the observed effect size, recombination fraction of 0.05, and heterozygosity of 0.75, 35 dogs in the backcross of the F1 to the Greyhound generation would yield linkage at a power of 0.8. For the DLS score, 35 dogs in the backcross to the Labrador Retriever generation would be required for linkage at the same power. For OSS, 45 dogs in the backcross to the founding Labrador Retrievers would yield linkage at the same power. Fewer dogs were projected to be necessary to find linkage to hip OA. Testing for linkage to the DLS at 4 loci simultaneously, each controlling 25% of the phenotypic variation, yielded an overall power of 0.7 CONCLUSIONS AND CLINICAL SIGNIFICANCE: Based on this conservative single-marker estimate, this pedigree has the requisite power to find microsatellites linked to susceptibility loci for hip dysplasia and hip OA by breeding a reasonable number of backcross dogs.     

Chronic lymphocytic leukemia in the dog: 22 cases (1974-1984)

Chronic lymphocytic leukemia was diagnosed in 22 dogs. Diagnosis was based primarily on detection of lymphocytosis and bone marrow infiltration with small lymphocytes similar to those seen in the blood. More than 50% of the dogs had monoclonal gammopathy, and, of these, 40% had monoclonal light-chain (Bence Jones) proteinuria. Hyperviscosity syndrome was observed occasionally. Most dogs were treated with chemotherapy. For the 17 dogs treated greater than or equal to 30 days, the survival times ranged from 30 to 1,000 days.     

Pectineus tendon surgery for the management of canine hip dysplasia.

Pectineus tendonectomy is a useful procedure for relieving pain and rehabilitating the dysplastic dog in select cases. Relief of pain is believed to come from a combination of releasing tension on the hip joint capsule and providing a better loading contact surface on the articular cartilage owing to the increased abduction of the hind legs after surgery. Some pain relief also may come from the release of tension on the pectineus muscle. The modified procedure described in this article results in less seroma formation and less reattachment of the severed ends of the pectineus tendon of origin than the procedure originally described by the author.     

Surgical treatment of epulides in dogs: 25 cases (1974-1984)

Epulides were diagnosed and surgically removed in 25 dogs. Histologic examination of the epulides indicated that 40% (10/25) were acanthomatous, 32% (8/25) were ossifying, and 28% (7/25) were fibromatous. Recurrence of the tumor directly resulted in the death of 2 dogs. One of these dogs died of malnutrition 13 months after removal of an ossifying epulis, and regrowth of an acanthomatous epulis that was not resected completely resulted in malnutrition and death in another dog 6 months after surgery. Malignant transformation was observed in a third dog 6 months after removal of an ossifying epulis when an osteosarcoma developed where the epulis had been removed. The range of survival was 6 to 134 months, mean survival time was 43.1 months, median survival time was 49 months, and 1-year survival rate was 92%. Satisfactory long-term tumor control was achieved by aggressive surgical treatment of epulides.     

Collagen type III:I composition in hip joints of dogs susceptible to nip dysplasia

Collagen type III:I ratios were measured in the coxofemoral joint capsules of dogs susceptible to hip dysplasia, dogs with hip dysplasia and healthy controls. The ratio was higher in those dogs susceptible to hip dysplasia than in the controls. These differences could explain the joint hypermobility seen in dogs with hip dysplasia.     

Clinical hip dysplasia in growing dogs: the long-term results of conservative management

The long-term results of conservative management in 68 immature dogs with clinical and radiographic evidence of hip dysplasia are described. Seventy-six per cent of the dogs had minimal gait abnormalities despite radiological evidence of moderate or severe osteoarthrosis.     

Estimation of genetic parameters for hip dysplasia in Czech Labrador Retrievers

The objective of this study was to estimate the genetic parameters, genetic trends and breeding values using linear model (LM) and threshold model (TM) for the development of hip dysplasia (HD) in Labrador Retrievers in the Czech Republic (n = 3151). The right and left hip joints were evaluated separately using the Fédération Cynologique Internationale scoring system. Four linear and four TMs were tested for the correct estimation of genetic parameters. All the tested models utilized fixed effects of sex, assessor, year of birth, regression of age at evaluation, random direct genetic effects and the effect of the animals' permanent environments. The models differed in the inclusion of the following effects: fixed effects of regression of inbreeding coefficient, random maternal effect and random effect of the maternal permanent environment. Compared to the TM, the LM provided lower coefficients of direct (0.25-0.29 versus 0.26-0.35) and maternal heritability (0.01-0.02 versus 0.03-0.05), repeatability (0.76-0.77 versus 0.78-0.83) and of the correlation between direct and maternal effects (-0.55 to -0.21 versus -0.80 to -0.27). In the tested models, no statistical significance was found for fixed regression of inbreeding coefficients or for the random effect of the permanent maternal environment. In spite of the similarity of the LM and TM results, the TM is recommended as the more suitable model for estimating genetic parameters and subsequent breeding values for HD in Labrador Retrievers in the Czech Republic.