Update of a retrospective cohort study of changes in hip joint phenotype of dogs evaluated by the OFA in the United States, 1989-2003.

OBJECTIVE: To determine whether there has been improvement in canine hip joint phenotype classifications of dogs whelped from 1989 to 2003 by the Orthopedic Foundation for Animals (OFA), by examining results of radiographic evaluations and identifying any trends in percentages of dogs classified as having desirable hip joint phenotypes. STUDY DESIGN: Retrospective cohort study. SAMPLE POPULATION: OFA radiographic classifications (n=431,483) on dogs whelped between 1989 and 2003. METHODS: Numbers and percentages of dogs classified by hip joint phenotypes were determined for 2-year cohorts. Differences between breeds and sexes were assessed using the Fisher's exact test, and odds ratios with 95% confidence intervals were calculated to express associations. The Cochran-Armitage test for trend was calculated to identify significant trends over time. RESULTS: There were statistically significant (P<.05) increases in the proportion of all breeds of dogs evaluated as excellent and good from 1993 to 2003, controlling for gender and age at evaluation. Labrador Retrievers, Bernese Mountain Dogs, and Rottweilers had the highest proportions of excellent and good scores, and the highest rates of improvement in excellent and good scores were seen in Bernese Mountain Dogs and Rottweilers. CONCLUSIONS: Results support the contention that there have been improvements in hip joint phenotype classifications in dogs in the United States since the previous study (1989-1992), through increases in the proportion of dogs receiving excellent and good classifications. CLINICAL RELEVANCE: Hip joint phenotype classifications can be used by dog breeders to develop breeding programs to improve the hip joints of future generations of dogs.

Genetic improvement of canine hip dysplasia through sire selection across countries.

Breeding against canine hip dysplasia (HD) may benefit from the importation of foreign sires. When foreign sires are evaluated on a different HD scale, this may diminish the efficacy. Using stochastic simulations, we evaluated genetic change and inbreeding levels for different scenarios of importing sires with high genetic merit for HD. Population size and genetic parameters (e.g. heritability, accuracy of selection, genetic correlation) were based on actual data for HD in Golden retrievers and Labrador retrievers in the UK and Sweden. For countries with different HD scales and an estimated breeding value (EBV) evaluation in place, the importation was useful if imported sires had EBV rankings in the top 50% and if genetic correlations between EBV systems were above 0.85. When importing sires with EBV rankings in the top 10%, moderate accuracies of EBVs (>0.40) and moderately strong genetic correlations (>0.70) were needed. Selection against HD without the importation of sires may increase inbreeding levels, while the importation of sires can decrease inbreeding levels. For national genetic evaluation and selection programmes, importing sires with high genetic merit can be an effective breeding strategy, but care is needed to estimate reliable EBVs.

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. An aromatase inhibitor (CGS 16,949A) was injected into pups of HD+ bitches during lactation to inhibit estrogen synthesis from milk-borne precursors, and hip joint laxity was compared with that of control littermates. Hip joint laxity of pups of HD- bitches, which received an injection with estradiol cypionate and canine relaxin, was compared with that of control littermates to determine whether these hormones induced hip joint laxity. RESULTS: High concentrations of estrogens and relaxin were found in milk of HD+ and HD- bitches throughout lactation. Serum concentrations of milk-derived relaxin and total estrogens were similar in all pups, but estradiol-17B was detected only in pups of HD+ bitches. Hip joint laxity was reduced in pups that received CGS 16,949A. Hip joint laxity was INCREASED IN PUPS OF HD- BITCHES THAT RECEIVED ESTRADIOL CYPIONATE AND RELAXIN. CONCLUSIONS AND CLINICAL RELEVANCE: Milk-borne maternal hormones and precursors were absorbed into the circulation of canine neonates and may play a role in hip joint laxity in HD+ pups. Phenotypic expression of hip dysplasia may therefore be preventable by antihormone treatment.

Effect of a commercially available fish-based dog food enriched with nutraceuticals on hip and elbow dysplasia in growing Labrador retrievers.

The aim of this study was to evaluate the prevalence of hip and elbow dysplasia in a group of growing Labrador retrievers fed a fish-based diet enriched with nutraceuticals with chondroprotective properties. The puppies ranged from 3 to 12 mo of age and were divided into 2 groups, each fed a different diet. The control diet consisted of a high quality, chicken-based dog food, while the test diet was a fish-based dog food, enriched with nutraceuticals. Hip and elbow joints were radiographed and scored at 6 and 12 mo of age. Overall, 42 dogs completed the study. At 12 mo of age, no differences were found between the groups in the prevalence of hip and elbow dysplasia, although dogs fed the fish-based food enriched with nutraceuticals had a less severe grade of osteoarthritis at 12 mo. It was concluded that the fish-based diet with nutraceuticals did have beneficial effects on the development of severe osteoarthritis.

L'objectif de la présente étude était d'évaluer la prévalence de dysplasie de la hanche et du coude dans un groupe de chiens Labrador en croissance nourris avec une diète à base de poisson enrichie de neutraceutiques ayant des propriétés chondroprotectrices. L'âge des chiots variait de 3 à 12 mois et ils ont été divisés en deux groupes, chacun étant nourri avec une diète différente. La diète témoin consistait d'un aliment de haute qualité pour chien à base de poulet, alors que la diète test était un aliment pour chien à base de poisson et enrichi avec des neutraceutiques. Les articulations des hanches et des coudes ont été radiographiées à 6 et 12 mois d'âge. Un total de 42 chiens a complété l'étude. À 12 mois d'âge, aucune différence n'a été trouvée entre les groupes dans la prévalence de dysplasie de la hanche et du coude, bien que les chiens nourris avec la diète à base poisson enrichie de neutraceutiques avaient un score d'ostéoarthrite moins sévère à 12 mois. Il a été conclu que la diète à base de poisson enrichie de neutraceutiques avait des effets bénéfiques sur le développement d'ostéoarthrite sévère.(Traduit par Docteur Serge Messier).

Evaluation of a circumferential femoral head osteophyte as an early indicator of osteoarthritis characteristic of canine hip dysplasia in dogs.

OBJECTIVE: To determine the relationship between a circumferential femoral head osteophyte (CFHO) and osteoarthritis characteristic of canine hip dysplasia, and to ascertain whether CFHO, like osteoarthritis, varies between diet-restricted and control-fed dogs. DESIGN: Longitudinal cohort study. ANIMALS: 48 Labrador Retrievers. PROCEDURES: Dogs were paired by size, sex, and litter and assigned to 1 of 2 equal groups at 2 months of age. The control-fed group was fed ad libitum, and the diet-restricted group was fed 25% less on a pairwise basis of the same diet for life. The dogs' hip joints were radiographed yearly for life. Each radiograph was evaluated for radiographic signs of osteoarthritis characteristic of hip dysplasia and for the presence and severity of a CFHO. RESULTS: 41 of the 48 (85.4%) dogs had a CFHO, which was detected at a median age of 5.4 years, and 33 of those 41 (80.5%) developed radiographic evidence of osteoarthritis. Nineteen (79.2%) dogs in the diet-restricted group and 22 (91.7%) in the control-fed group had a CFHO at a median age of 9 and 3 years, respectively. Of the dogs with a CFHO, 12 (63.2%) in the diet-restricted group and 20 (90.0%) in the control-fed group developed radiographic evidence of osteoarthritis characteristic of hip dysplasia at a median age of 11 and 6.5 years, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated a relationship between the CFHO and subsequent development of radiographic signs of osteoarthritis. If a CFHO is present in Labrador Retrievers, it might be considered an early indicator of osteoarthritis.

Lifelong diet restriction and radiographic evidence of osteoarthritis of the hip joint in dogs.

OBJECTIVE: To evaluate the effects of diet restriction on development of radiographic evidence of hip joint osteoarthritis in dogs. DESIGN: Longitudinal cohort study. ANIMALS: 48 Labrador Retrievers from 7 litters. PROCEDURES: Forty-eight 6-week-old puppies from 7 litters were paired with littermates by sex and weight, and each pairmate was randomly assigned to 1 of 2 groups of 24 dogs each. Starting at 8 weeks of age, 1 group was fed ad libitum (control fed) and the other was fed 25% less (restricted fed) of the same diet for life on a pairwise basis. The dogs' hip joints were radiographed in the standard ventrodorsal hip-extended view at multiple intervals prior to 1 year of age and at annual intervals thereafter on the basis of birth anniversary. A board-certified radiologist unaware of group assignment scored the radiographs for evidence of osteoarthritis. RESULTS: Prevalence of radiographic evidence of hip joint osteoarthritis in all dogs increased linearly throughout the study, from an overall prevalence of 15% at 2 years to 67% by 14 years. Restricted-fed dogs had lower prevalence and later onset of hip joint osteoarthritis. Median age at first identification of radiographic evidence of hip joint osteoarthritis was significantly lower in the control-fed group (6 years), compared with the restricted-fed group (12 years). CONCLUSIONS AND CLINICAL RELEVANCE: Restricted feeding delayed or prevented development of radiographic signs of hip joint osteoarthritis in this cohort of Labrador Retrievers. Lifetime maintenance of 25% diet restriction delayed onset and reduced severity of hip joint osteoarthritis, thus favorably affecting both duration and quality of life. In addition, the data indicated that development of hip joint osteoarthritis was not bimodal in these dogs but occurred as a continuum throughout life.

Controlling canine hip dysplasia in Finland.

The aim of the study was to evaluate the Finnish Kennel Club's hip-dysplasia screening and control programs. As a retrospective study, records of hip-dysplasia screening of 69,349 dogs in 22 breeds that were born in 1988-1995 were analyzed and compared to data from prior to 1988. In most breeds, no significant changes in dysplasia prevalence could be found. In English cocker spaniels, golden and Labrador retrievers and Rottweilers a significant decrease - but in boxers, Dobermans, German Shepherd dogs and rough collies a significant increase - in prevalence was detected. In flat-coated retrievers overall prevalence increased - but the prevalence of severe hip-dysplasia decreased significantly during the study period. The present control program has not resulted in fast progress. Selecting against hip-dysplasia cannot be expected to be very effective, when based only on mass selection on phenotypic observations. Predicted breeding values based on progeny testing would probably give better results. Also, breeders' compliance and commitment to programs is not always high and other selection criteria in breeding are thought to be more important. Modern society has high demands for animal welfare and consumer issues, and breeders and kennel societies should pay more attention to health issues in breeding pedigreed dogs.

An epidemiological approach to prevention and control of three common heritable diseases in canine pedigree breeds in the United Kingdom.

This paper reviews recent epidemiological research in the United Kingdom for controlling deafness in Dalmatians, glaucoma in flat coated retrievers and great Danes and hip dysplasia in flat coated retrievers, Newfoundlands, Gordon setters and Labrador retrievers. These studies assessed the prevalence of the disease, identified the factors affecting prevalence, and developed predictive statistical models of offspring/parent relationships. For each disease/breed combination, the research identified those sires and dams that might justifiably be regarded as suitable/unsuitable as potential parents in a selective breeding strategy to control or prevent the disease. Future progress in the control of these diseases is likely to come from greater understanding of their mode of inheritance. Insight, even for these complex diseases, can be derived from further detailed statistical evaluation of datasets such as those described in this paper.

Effects of intramuscular administration of glycosaminoglycan polysulfates on signs of incipient hip dysplasia in growing pups.

We tested the hypothesis that treatment of growing, susceptible (to hip dysplasia) pups by IM administration of glycosaminoglycan polysulfates would mitigate the signs of incipient hip dysplasia. In 1 experiment, 7 pups, selected at random from 2 litters, were administered glycosaminoglycan polysulfates (2.5 mg/kg of body weight, IM) twice weekly, and 7 control pups from the same litters were given sterile buffered 0.9% saline solution from the age of 6 weeks to 8 months. Hip joints were examined by radiography, with pups in the standard, limbs-extended position. At 8 months of age, all pups in this experiment did not manifest femoral head subluxation radiographically. The Norberg angle, a measure of coxofemoral congruity, improved from a mean +/- SEM value of 102 degrees +/- 1 degrees in controls to 106 degrees +/- 1 degrees in treated pups (P = 0.008). Pups were not subjected to necropsy. In the second experiment, 8 pups were selected at random from 2 litters and were administered 5 mg of glycosaminoglycan polysulfates/kg, IM, twice weekly from 6 weeks to 8 months of age. Similarly, 8 control pups were administered saline solution. At 8 months of age, hip joints were examined by radiography with pups in the standard position; at necropsy, intra-articular tissues were evaluated macroscopically and biochemically. Of 8 treated pups, none had subluxation radiographically, whereas 4 of 8 control dogs had femoral head subluxation. Mean Norberg angle on the radiographs was 109.7 degrees +/- 1.6 degrees for the treated group and was 101.5 degrees +/- 1.6 degrees for controls, representing a mean improvement in coxofemoral congruity of 8.2 degrees in the treated pups.(ABSTRACT TRUNCATED AT 250 WORDS)

Genetics of canine hip dysplasia.

OBJECTIVE: To document genetic progress in improving hip quality of dogs maintained in a closed breeding colony to produce dogs for training as guides for blind people. DESIGN: Prospective analysis of hip quality records from a breeding trial that encompassed 3 full generations and included some dogs born into the fourth and fifth generations. ANIMALS: Hip quality was assessed for 2,037 German Shepherd Dogs and 1,821 Labrador Retrievers from 1980 to 1996. PROCEDURE: A subjective hip score assigned by 1 radiologist was used to assess hip quality during the study period. In the past 8 years, the distraction index was also used. Genetic change was produced by selecting a small percentage of dogs to be parents of the next generation. Dogs were selected to become parents of the next generation on the basis of estimated breeding values. These were calculated by combining observed values of individual dogs with known relationships in the population pedigrees to predict which dogs were the best candidates for selection as parents. RESULTS: In < 5 generations of selection, the percentage of German Shepherd Dogs with canine hip dysplasia at 12 to 16 months of age decreased from 55 to 24%. Among Labrador Retrievers, the percentage decreased from 30 to 10%. CLINICAL IMPLICATIONS: This report gives practitioners documented proof that genetic selection will work to improve hip quality. Dog breeders must be advised to be patient, however, to allow enough generations to elapse to make meaningful genetic change.

Effects of limited food consumption on the incidence of hip dysplasia in growing dogs.

Forty-eight 8-week-old Labrador Retrievers were allotted to 2 groups of 24 dogs each; 1 group was fed ad libitum and the other group was given 25% less of the same feed until the dogs were 2 years old. Radiography of the hip joints was done when the dogs were 30, 42, 54, 78, and 104 weeks old. Subluxation was measured by the Norberg angle on radiographs made with the dog in the standard (extended limb) position. Independent of age at which the radiography was done, there was less subluxation of the femoral heads in the limit-fed dogs. Using the Swedish method of hip joint evaluation on the same radiographs, it was found that fewer dogs on limited food intake had signs of hip dysplasia. Radiographs done when dogs were 2 years old, for all the methods used (Norberg angle in standard and frog-limb position, the Orthopedic Foundation for Animals [OFA] score, and the Swedish score), revealed less hip dysplasia (less joint subluxation and less degenerative joint disease) in the limit-fed dogs. Using the OFA method, 7 of the 24 limit-fed dogs and 16 of the 24 ad libitum-fed dogs were diagnosed as having hip dysplasia. Similarly, using the Swedish method, 5 of the 24 limit-fed dogs and 18 of the 24 ad libitum-fed dogs were diagnosed as having hip dysplasia. The food-intake-related differences were significant both for the OFA score and for the Swedish score.(ABSTRACT TRUNCATED AT 250 WORDS)

A review of the progress in canine hip dysplasia control in Britain.

Results of the British Veterinary Association/Kennel Club program for controlling canine hip dysplasia (CHD) were reviewed for 6 breeds to determine whether there had been any progress in reducing the prevalence of CHD. Although there was a decrease in mean hip dysplasia score for some of the 6 breeds when results for the 1991 to 1995 period were compared with those for 1987 to 1990, there were not any consistent trends in 5 of the breeds, and there was a clear worsening of the mean hip score in Siberian Huskies. In general terms, not only has there been a steady increase in the percentage of parents that were scored or, more accurately, an increase in the use of scored parents when breeding, but in broad terms the weighted mean score for the parents was lower (ie, better) than the mean score for all dogs in the breed during each period. In all breeds, there appeared to have been some selection to reduce total hip score, but in all but 1 instance, the expected result was not achieved, with actual values being higher (ie, worse) than those expected from theory. If the incidence of CHD is to diminish in Britain, then, as a first step, the Kennel Club must insist that, in affected breeds, only progeny of scored parents may be registered. Thereafter, a gradual tightening of the parental scores that will be accepted in each breed should be attempted, and best linear unbiased predictor-type indices should be established and applied to sires and dams to ensure wider usage of the better parents.

Trends in hip dysplasia control: analysis of radiographs submitted to the Orthopedic Foundation for Animals, 1974 to 1984.

From 1974 through 1984, the Orthopedic Foundation for Animals evaluated 143,218 radiographic submissions representing 151 breeds of dogs. All breeds from which there were 35 or more evaluations had some frequency of dysplasia. Seventy breeds, each with over 100 submissions, were tabulated and ranked according to frequency of hip dysplasia. Frequency of dysplasia varied from 0.6% in the Borzoi to 46.9% in the Saint Bernard. These data were compared with data obtained earlier (1966 to 1973) on evaluations in 38 breeds for changes in frequency. There was significant (P less than 0.05) reduction in frequency of dysplasia in 27 breeds, a significant (P less than 0.05) increase in frequency in only 1 breed (German Shorthaired Pointer), and no significant change in frequency in 10 breeds. The median significant decrease was 22.4%, and the range was from 3.1% in the Chesapeake Bay Retriever to 48.7% in the Keeshond. The reduction in frequency of hip dysplasia demonstrated the value of a control program. There were 5 breeds with a significant (P less than 0.05) decrease in frequency of dysplasia that had over 5,000 evaluations from 1974 to 1984. The decreases in frequency were independent of changes in American Kennel Club registrations for these breeds (a dramatic decline in registrations for the German Shepherd Dog and Old English Sheepdog, and a dramatic increase for the Rottweiler, Golden Retriever, and Labrador Retriever). Frequency regressed linearly in the German Shepherd Dog and Old English Sheepdog, but regressed nonlinearly in the other 3 breeds. The percentage reduction in frequency from the base frequency (1966 to 1973) for these breeds was 17.5% for the German Shepherd Dog, 23.1% for the Old English Sheepdog, 9.1% for the Rottweiler, 10.1% for the Golden Retriever, and 6.8% for the Labrador Retriever.

Prevalence and inheritance of and selection for hip dysplasia in seven breeds of dogs in Sweden and benefit: cost analysis of a screening and control program.

OBJECTIVE: To determine the prevalence and changes over time in the prevalence of hip dysplasia; to ascertain whether prevalence or severity of hip dysplasia was associated with sex of the dogs, age at which coxofemoral joint status was evaluated, or ancestral background; to determine the effects of selective breeding; and to conduct an economic evaluation of the hip dysplasia program operated by the Swedish Kennel Club. DESIGN: Analysis of radiographic evaluations of coxofemoral joint conformity. ANIMALS: 83,229 dogs from 7 breeds registered by the Swedish Kennel Club. PROCEDURE: All radiographs were scrutinized by a single radiologist (LA), and coxofemoral joint conformation was classified as normal or dysplastic, with the degree of dysplasia classified as 1,2,3, or 4. RESULTS: Decreasing prevalence of hip dysplasia corresponding to selection of breeding stock and high heritabilities was found. Sex differences were documented in 3 of the breeds. This was interpreted as breed differences in the distribution of genes related to hip dysplasia. Economic analyses showed that costs of screening and registration of coxofemoral joints was less than the value of dogs estimated to have been saved from moderate, severe, or very severe hip dysplasia in 6 of the breeds. CLINICAL IMPLICATIONS: Documented effects of age suggest that all dogs should be screened at the same age, rather than screening a few dogs at an older, more revealing age. In screening and control programs based on an open registry with access to family records, decreasing prevalence of hip dysplasia can be expected, and related to selection of breeding stock.

Canine hip dysplasia and the breeder. A layman's point of view.

Many, though certainly not all, breeders are becoming fairly knowledgeable about CHD and other joint problems. The veterinarian should encourage prevention through selective breeding and lead the client to further understanding of the disorders. Breeders need help in separating scientific evidence from insufficiently tested hypotheses based on testimonials. "Quick-and-easy" cures can be exposed and discounted with just a little search of the literature. The veterinarian's job is similar to that of the teacher in the old one-room country school: some client may have to be taught the basics, whereas those in other stages of progress receive different help. Breeders perhaps need more assistance than do pet owners, because they will affect future generations of dogs. The veterinarian who concentrates on building a trust relationship based on shared facts and a sincere desire to contribute to the well-being of his clients (and his patients) will enjoy a most rewarding relationship with them.

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.

Diagnosis of canine hip dysplasia and selection against this trait.

N, the Norberg-Olsson value, when regarded as the single predictor of FS in the total research subpopulation, leads to an unacceptably high proportion of misclassifications. These misclassifications are found to be much reduced in number on elimination of all animals suffering from bone deformities (BD) as perceivable on the radiographs. Discriminant analysis, applied to the findings in 915 Rottweilers, yields the combination of a suitable high N with the absence of perceivable bone deformities as a more acceptable predictor for FS, specially applicable in borderline cases.

[The control of hip dysplasia in Switzerland. A retrospect of the past 24 years]. / Die Bekämpfung der Hüftgelenksdysplasie in der Schweiz. Ein Rückblick auf die vergangenen 24 Jahre.

Examination of over 3700 dogs has proven that 42% of all purebred dogs in Switzerland are affected by CHD despite control programs for the last 30 years. Breeding with dysplastic dogs and lack of progeny control are responsible for this slow progress.

Breeding healthier dogs in Sweden.

Preventive measures in small animal veterinary medicine include not only deworming, feeding and vaccination but also selection of breeding stock with reference to health and longevity. Good cooperation between the veterinary profession and the Swedish Kennel Club in the examination of breeding stock is described. Successful eradication programs against Hip Dysplasia, Elbow Arthroses and Hereditary Eye Defects are chosen as examples of what has been achieved so far. Less extensive and newer programs against Hemophilia A and Progressive Nephropathy are described as well as a recently instituted Inventory of Hereditary Defects and the preparation of educational material on risks involved when certain anatomical features are exaggerated in purebred dogs. A cost-benefit analysis has proven the value of screening programs for hereditary defects with both negative as well as positive results on public records