Effect of dam and sire qualitative hip conformation scores on progeny hip conformation

OBJECTIVE: To determine in dogs what effect using hip conformation scores assigned by the Orthopedic Foundation for Animals (OFA) as a criterion for breeding selections would have on hip conformation scores of the progeny. DESIGN: Longitudinal study. ANIMALS: English Setters, Portuguese Water Dogs, Chinese Shar-peis, and Bernese Mountain Dogs for which OFA hip conformation scores were known. PROCEDURE: Pedigree data were obtained from the national breed clubs and the American Kennel Club and merged with data from the OFA hip conformation score database. An ANOVA was used to evaluate the effects of sex, age at the time of radiographic evaluation, and year of birth on the variation in hip conformation scores among the progeny. Heritability was estimated by use of within-year midparent offspring regression analyses. RESULTS: Significant differences in progeny hip conformation scores between sexes were not detected, but age at the time of radiographic evaluation and year of birth had a significant effect on hip joint conformation of the progeny. Estimated heritability (mean +/- SE) was 0.26 +/- 0.03, and dam and sire hip conformation scores had a significant effect on progeny hip conformation scores. Annual decreases in percentage of dysplastic progeny and increases in percentages of progeny and breeding dogs with phenotypically normal hip joint conformation were detected. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that hip conformation scores have moderate heritability in dogs and selection of breeding stock with better hip conformation scores will increase the percentage of progeny with phenotypically normal hip joint conformation.     

Association between radiographic assessment of hip status and subsequent incidence of veterinary care and mortality related to hip dysplasia in insured Swedish dogs

Our objective was to evaluate the association between grading of hip status as assessed by radiographic examination (hip screening) and subsequent incidence of veterinary care and mortality related to hip dysplasia (HD) in five breeds of insured dogs in Sweden. Screening results for hip status from the Swedish Kennel Club and data on veterinary care and mortality from the insurance company Agria were merged based on the registration number of the dog. Dogs of five breeds (Bernese Mountain Dogs, German Shepherds, Golden Retrievers, Labrador Retrievers, and Rottweilers) screened during 1995–2004 and covered by an insurance plan for veterinary care or life at the time of screening were included. The study populations included between 1667 and 10,663 dogs per breed. Breed-specific multivariable Cox proportional-hazards analyses were performed to evaluate the impact of radiographic hip status on time from hip screening to first HD-related veterinary and life claim, respectively. The effects of gender, birth season, and a time-varying covariate of year were also studied. Additional analyses, on the five breeds combined, were performed to investigate the effects of hip status, breed, and the interaction between hip status and breed. The effect of hip status was highly significant (P < 0.001) for both life and veterinary claims related to HD in all five breeds with increased hazard ratio (HR) for deteriorating hip status. Dogs with moderate or severe hip status at screening had a markedly increased hazard of HD-related veterinary care and mortality compared with dogs assessed as free or mild. The time-varying covariate of year showed a significantly higher HR in the last time period for German Shepherds and Labrador Retrievers in the analyses of veterinary claims. In the analyses on all five breeds, German Shepherds had the highest HR for both veterinary care and mortality related to HD, followed by Bernese Mountain Dogs. Golden and Labrador Retrievers had the lowest HR. The effect of hip status on the hazard was the same irrespective of breed. However, as a consequence of differences between breeds in overall risk, the predictive ability of screening results for subsequent incidence of HD-related problems for individual dogs was breed-dependent. Based on the strong association between radiographic hip status and incidence of HD-related veterinary care and mortality, and the previously reported moderate heritability of hip status, we conclude that selection based on screening results for hip status can be expected to reduce the risk of HD-related clinical problems.     

Quantification of measurement of femoral head coverage and Norberg angle within and among four breeds of dogs

OBJECTIVE: To report values for percentage coverage of the femoral head (PC) and Norberg angle (NA) in 4 common breeds of dogs and to determine values for each that distinguish between normal and dysplastic hip status on the basis of Orthopedic Foundation for Animals (OFA) hip evaluation. ANIMALS: 1,841 dogs 24 to 48 months of age that were Labrador Retrievers (455), Golden Retrievers (423), Rottweilers (545), or German Shepherd Dogs (418). PROCEDURE: Retrospective analysis of NA and PC measured from standard OFA ventrodorsal pelvic radiographs from 4 breeds of dog. RESULTS: Norberg angle ranged from 67.4 to 124.4 degrees for Labrador Retrievers, 59.7 to 128.6 degrees for Rottweilers, 70.2 to 119.4 degrees for Golden Retrievers, and 55.3 to 121.3 degrees for German Shepherd Dogs. The PC ranged from 6.5 to 79.9% for Labrador Retrievers, 5.7 to 79.5% for Rottweilers, 8.3 to 79.3% for Golden Retrievers, and 5.4 to 83.7% for German Shepherd Dogs. On the basis of logistic regression modeling for determining normal versus abnormal hip status for all 4 breeds, cutoff points for NA were <105 degrees and PC were <50%. CONCLUSIONS AND CLINICAL RELEVANCE: Results of our study indicate that cutoff points of NA of 105 degrees and PC of 50% do not differentiate normal versus dysplastic hip status. Each of the 4 breeds had different values for NA and PC that distinguished normal from dysplastic hip status.     

Prior joint disease is associated with increased risk of periarticular histiocytic sarcoma in dogs

Periarticular histiocytic sarcoma (PAHS) is the most common synovial tumour in dogs and is characterized by aggressive local disease with a high rate of distant metastasis. Previously, an association between PAHS and prior joint disease has been demonstrated in the Bernese Mountain Dog breed and suggested in the Rottweiler. We hypothesized that this association would be present in other breeds and investigated this via a retrospective, case‐controlled analysis. Cases were dogs diagnosed with PAHS of the stifle or elbow. Controls were age, breed and sex‐matched dogs without a diagnosis of histiocytic sarcoma. Diagnosis of prior joint disease was determined based on review of medical records and direct veterinarian and owner communications. Data were evaluated using logistic regression, 2‐sampled t tests, and chi‐squared analysis. Our study population consisted of 28 cases and 46 controls, including Flat‐Coated, Golden and Labrador Retrievers, Rottweilers, English Bulldogs, Shih Tzus, Australian Shepherds, Staffordshire Terriers and mixed breed dogs. Dogs with PAHS were more likely to have prior joint disease in the tumour‐affected joint compared with the control population (odds ratio [OR] = 13.42, P < .0001, 95% confidence interval [CI] = 4.33‐48.63). A total of 88.2% of dogs with stifle PAHS had prior joint disease in their tumour‐affected joint, most commonly cranial cruciate ligament rupture. This study confirms that the previously noted association between prior joint disease and PAHS in Bernese Mountain Dogs also applies to other breeds. Additional studies are needed to further investigate for a causal relationship.     

RADIOGRAPHIC FINDINGS IN CANINE MALIGNANT HISTIOCYTOSIS

Radiographs of 19 dogs diagnosed as having malignant histiocytosis were examined. The most common abnormalities involved the spleen (10), liver (6), lymph nodes (6 thoracic, 4 abdominal), and lungs (6). Other abnormalities involved the spinal column (3), and bones (2). Correlations were made between radiographic appearance and histologic diagnoses. As has been reported, Bernese Mountain Dogs were found to be significantly more often affected than other breeds. Rottweilers and Golden Retrievers were also found to have higher incidence rates. Viewed radiographically, treatment appeared to have little impact on the course of the disease.     

Estimates of prevalence of hip dysplasia in Golden Retrievers and Rottweilers and the influence of bias on published prevalence figures

OBJECTIVE: To estimate prevalence of canine hip dysplasia (CHD) in Golden Retrievers and Rottweilers and identify sources of bias in published reports. DESIGN: Prospective study. ANIMALS: 200 clinically normal Golden Retrievers and 140 clinically normal Rottweilers between 24 and 60 months of age referred for hip evaluation (group 1) and 93 clinically normal dogs evaluated for Orthopedic Foundation for Animals (OFA) hip certification (group 2). PROCEDURE: Hip-extended pelvic radiographs from group 1 dogs were screened for CHD. Radiographs were evaluated twice; the first interpretation used an OFA-type subjective 7-point scoring system, and the second included the caudolateral curvilinear osteophyte as an additional sign of degenerative joint disease. The OFA submission rate of group 2 dogs was determined from the number of official reports returned from the OFA. RESULTS: Prevalence of CHD in Golden Retrievers ranged from 53% to 73% and in Rottweilers ranged from 41% to 69%. Among dogs referred for OFA evaluation, radiographs from 49 (53%) were submitted to OFA. Of submitted radiographs, 45 (92%) were normal; of radiographs not submitted, 22 (50%) were normal. Radiographs with normal-appearing hips were 8.2 times as likely to be submitted to the OFA. Compared with Golden Retrievers, Rottweiler radiographs were significantly more likely to be submitted for OFA certification. CONCLUSIONS AND CLINICAL RELEVANCE: Prevalence of CHD in these 2 breeds may be much higher than previously reported in the United States. Results suggest substantial bias in the OFA database, which causes lower estimates of prevalence of CHD.     

Osteological and morphometric observations on intervertebral joints in the canine pre-diaphragmatic thoracic spine (Th1-Th9)

The incidence of facet aplasia was investigated in three groups of pure-bred dogs. We examined large breeds (Rough Collies, Doberman Pinschers, Rottweilers, Bernese Mountain Dogs, German Shepherd Dogs), chondrodystrophic breeds (Dachshunds, Pekinese dogs), and small breeds (Yorkshire Terriers, Maltese dogs). Uni- or bilateral aplasia of zygapophyseal (facet) joints was exclusively found in juvenile and adult small dogs, in which the incidence of aplasia ranged from between 26% (Th1) and 63% (Th8). There was no evidence that aplasia of zygapophyseal joints increases the risk of developing intervertebral disc disease or deformative spondylosis in small breeds. By applying the findings of previous empirical studies on intervertebral disc geometry and its biomechanical behaviour on the present morphometric results, there was an indication that the intervertebral disc may well compensate for the functional loss of aplastic zygapophyseal joints in small dogs. Biomechanical factors and their potential role as inducing agents of facet aplasia in the pre-diaphragmatic thoracic spine are also discussed.     

Correction of Rotational Deformity of the Pes with External Skeletal Fixation in Four Dogs

Objective— To report unilateral correction and initial stabilization with external skeletal fixation (ESF) of metatarsal rotation in 4 immature Bernese Mountain Dogs.
Study Design— Case series.
Animals— Bernese Mountain Dogs (n=4).
Methods— The limb deformity, including degree and origin of the deformity at the level of the proximal intertarsal joint and involvement of the central tarsal bone, was characterized by clinical and radiographic assessment. Unilateral surgical correction of the most severely affected limb was performed by disrupting the ligaments and debriding the articular cartilage of the proximal intertarsal joint to allow for derotation of the deformity and arthrodesis of the proximal intertarsal joint stabilized with either circular or linear ESF.
Results— Initial metatarsal rotation of the corrected limbs ranged from 60° to 80° of external rotation (mean, 72.5°). Three limb corrections were stabilized with circular ESF and 1 with a biplanar linear ESF. Implants were removed at the time of radiographic bony union (range, 7–10 weeks; mean, 8.6 weeks). Residual deformity was minimal, ranging from 6° to 15° (mean, 11°). Two minor complications (loosening of 1 pin, serous drainage from 1 pin) resolved with treatment.
Conclusion— Correction of rotational deformity of the pes with intertarsal arthrodesis yielded an excellent clinical outcome, with only a mild residual deformity.
Clinical Relevance— Rotational metatarsal deformities can have a significant impact on gait, ambulation, and appearance. Correction of these deformities and stabilization with ESF and intratarsal arthrodesis can yield an excellent functional outcome, with improved gait and ambulation.     

The presence of antiphospholipid antibodies in healthy Bernese Mountain Dogs

Background

The role of antiphospholipid antibodies in the prolonged activated partial thromboplastin time (aPTT) previously identified in healthy Bernese Mountain Dogs remains unknown. In people, an isolated prolonged aPTT without evidence of bleeding might be because of a thrombophilic condition caused by antiphospholipid antibodies.

Objective

To examine if prolonged aPTT in healthy Bernese Mountain Dogs is because of antiphospholipid antibodies.

Animals

Twenty‐two healthy Bernese Mountain Dogs and 10 healthy adult dogs of various breeds.

Methods

Prospective case control study. Healthy Bernese Moutain Dogs were examined twice over 6 months. Dogs were investigated for the presence of lupus anticoagulants and anticardiolipin (aCL) antibodies by the use of multiple aPTT tests with low and high lupus anticoagulant sensitivities, a mixing study, and an ELISA test for aCL antibody optical density to detect solid phase antiphospholipid antibodies.

Results

In all, 15 of 22 healthy Bernese Mountain Dogs were positive for lupus anticoagulants. The Bernese Mountain Dogs had markedly higher levels of aCL antibodies compared with the control dogs (P = .006). In all, 7 of 21 of the Bernese Mountain Dogs were positive for both lupus anticoagulants and aCL antibodies, whereas 4 of 21 Bernese Mountain Dogs were negative for both.

Conclusions and Clinical Importance

Lupus anticoagulants and aCL antibodies could be the cause of prolonged aPTT in healthy Bernese Mountain Dogs. The importance of the antiphospholipid antibodies in the dogs remains unknown.     

Relationships between results of the Ortolani method of hip joint palpation and distraction index, Norberg angle, and hip score in dogs

OBJECTIVE: To determine whether results of the Ortolani method of hip joint palpation in dogs were related to distraction index (DI), Norberg angle, or radiographic hip score. DESIGN: Cross-sectional study. ANIMALS: 459 clinically normal dogs. PROCEDURE: Dogs were sedated for radiography and palpation of the hip joints. Results of hip joint palpation were classified as negative, mild positive, moderate positive, or severe positive. Distraction indices were measured for all dogs. Norberg angles were measured for 380 dogs for which ventrodorsal hip-extended radiographic projections were available. Hip scores assigned by the Orthopedic Foundation for Animals (OFA) were available for 95 dogs. RESULTS: Age, weight, and sex were not significantly associated with results of hip joint palpation. There was moderate correlation between results of hip joint palpation and DI (r = 0.636), low-moderate correlation between results of hip joint palpation and OFA hip scores (rs = 0.437), and weak negative correlation (r = -0.236) between results of hip joint palpation and Norberg angle. For joints without degenerative joint disease (DJD), there was a significant linear relationship between results of hip palpation and DI; however, for joint with DJD, there was not. Results of hip joint palpation were 5.3-fold as likely to be negative for dogs with DJD as for dogs without. CLINICAL IMPLICATIONS: Results of hip joint palpation were at best moderately correlated with radiographic measures of hip joint laxity. Therefore, hip joint palpation should be combined with hip-extended and stress radiography when assessing hip joint quality.     

Evaluation of a radiographic caudolateral curvilinear osteophyte on the femoral neck and its relationship to degenerative joint disease and distraction index in dogs

OBJECTIVE: To determine prevalence of a radiographic caudolateral curvilinear osteophyte (CCO) on the femoral neck in various breeds and age groups of dogs and to evaluate its contemporaneous relationship with degenerative joint disease (DJD) and distraction index (DI). DESIGN: Cross-sectional prevalence study. ANIMALS: 25,968 dogs, including 3,729 German Shepherd Dogs, 4,545 Golden Retrievers, 6,277 Labrador Retrievers, and 1,191 Rottweilers. PROCEDURE: Data from the University of Pennsylvania Hip Improvement Program database were analyzed, including ventrodorsal hip-extended, compression, and distraction radiographs. The CCO and radiographic signs of DJD were considered independent events and were interpreted as either present or absent. Statistical methods were used to evaluate the CCO as a possible risk factor for DJD and assess its association with DI, as measured by use of distraction radiography. RESULTS: When all breeds were pooled, DJD was detected in 8.6% of dogs, and the CCO was detected in 21.6% of dogs. Among dogs with a CCO, 25.1% had radiographic evidence of DJD. Among dogs without a CCO, only 4% had DJD. Dogs with a CCO were 7.9 times as likely to have DJD as were those without a CCO. Additionally, DI, weight, and age were significant risk factors for the CCO. CONCLUSION AND CLINICAL RELEVANCE: Results confirm the contemporaneous association between the CCO and DJD and that passive hip laxity, as measured by use of the DI, is associated with both the CCO and DJD.     

Use of routine ventrodorsal radiographic views of the pelvis to assess inclination of the wings of the sacrum in dogs

OBJECTIVE: To determine the ratio of ventral-to-dorsal transverse diameters between the wings of the sacrum on ventrodorsal radiographic views of the pelvis in large dogs and to validate the reliability of this morphometric analysis for functional interpretation. SAMPLE POPULATION: Pelvic specimens from 40 large-breed dogs and radiographs of 113 large-breed dogs. PROCEDURE: In an anatomic and radiographic evaluation, the transverse dorsal diameter (TVDS) and transverse ventral diameter (TVV) between the wings of the sacrum were evaluated in sacrum specimens and on corresponding radiographs of the pelvis and sacrum. The ratio between TVV and TVDS (VD ratio) was calculated. Intraobserver reliability was determined by calculation of the coefficient of variation. In a retrospective radiographic evaluation, the VD ratio was determined in Rottweilers, Golden Retrievers, and German Shepherd Dogs. Correlations between VD ratio and breed, age, and sex were tested. RESULTS: The VD ratio was significantly higher in Rottweilers than in Golden Retrievers and German Shepherd Dogs, denoting an oblique alignment of the sacral wings in Rottweilers (ie, the dorsal aspects of the sacral wings were located more medially than the ventral aspects) and an almost sagittal alignment in the other breeds. The VD ratio was significantly associated with age but not with sex. CONCLUSIONS AND CLINICAL RELEVANCE: Sagittal alignment of the wings of the sacrum is considered to be biomechanically less efficient. These results provide a basis for further studies to evaluate radiographic assessment of the sacroiliac joints similar to the evaluation for hip dysplasia.     

Breed risk of pyometra in insured dogs in Sweden

An animal insurance database containing data on over 200,000 dogs was used to study the occurrence of pyometra with respect to breed and age during 1995 and 1996 in Swedish bitches <10 years of age. A total of 1,803 females in 1995 and 1,754 females in 1996 had claims submitted because of pyometra. Thirty breeds with at least 800 bitches insured each year were studied using univariate and multivariate methods. The crude 12-month risk of pyometra for females <10 years of age was 2.0% (95% confidence interval = 1.9-2.1%) in 1995 and 1.9% (1.8-2.0%) in 1996. The occurrence of pyometra differed with age, breed, and geographic location. The risk of developing pyometra was increased (identified using multivariate models) in rough Collies, Rottweilers, Cavalier King Charles Spaniels, Golden Retrievers, Bernese Mountain Dogs, and English Cocker Spaniels compared with baseline (all other breeds, including mixed breed dogs). Breeds with a low risk of developing the disease were Drevers, German Shepherd Dogs, Miniature Dachshunds, Dachshunds (normal size), and Swedish Hounds. Survival rates indicate that on average 23-24% of the bitches in the databases will have experienced pyometra by 10 years of age. In the studied breeds, this proportion ranged between 10 and 54%. Pyometra is a clinically relevant problem in intact bitches, and differences related to breed and age should be taken into account in studies of this disease.     

Evaluation of the Norberg angle threshold: a comparison of Norberg angle and distraction index as measures of coxofemoral degenerative joint disease susceptibility in seven breeds of dogs

OBJECTIVE: To evaluate the thresholds of 2 radiographic methods used to determine coxofemoral joint laxity in 7 breeds of dogs. ANIMALS: Three hundred and fifty clinically normal dogs. STUDY DESIGN: Retrospective study. METHODS: Hip radiographs from 7 breeds of dogs were randomly selected from a database. None of the dogs had radiographic evidence of degenerative joint disease (DJD). Distraction index (DI) and Norberg angle (NA) were measured on these radiographs and compared with DI and NA thresholds for diagnosing DJD susceptibility derived from the literature and from evaluated Borzois. Dogs with a NA<105 degrees and a DI of < or =0.32 were considered false-positives and dogs with a NA> or =105 degrees and a DI of >0.32 were considered false-negatives. RESULTS: Mean age of all dogs was 22.9 months. Mean NA for all dogs was 99.37 degrees, and mean DI for all dogs was 0.44. Borzoi mean DI of was significantly less than the mean DI of the other 6 breeds. The highest (most hip laxity) Borzoi DI was 0.32, and the lowest (most hip laxity) Borzoi NA was 99 degrees. False-positive and false-negative diagnoses were identified in 6 of the 7 breeds. CONCLUSIONS: Using the NA threshold of 105 degrees (literature established threshold of susceptibility to DJD) resulted in a high percentage of false-negative and false-positive diagnoses. Breeds like the Labrador Retriever and Rottweiler would have large numbers of hip dysplasia susceptible dogs remain in the breeding population based on this NA threshold. False-positive diagnoses were common in breeds like the Australian Shepherd, Borzoi, and German Shepherd effectively eliminating hip dysplasia nonsusceptible dogs from the breeding population. CLINICAL RELEVANCE: The NA was not an accurate predictor of DJD susceptibility in these 7 breeds of dogs when using a NA threshold of 105 degrees.     

New concepts of coxofemoral joint stability and the development of a clinical stress-radiographic method for quantitating hip joint laxity in the dog

From mechanical principles and postmortem observations of coxofemoral joints of dogs, a hydrostatic mechanism influencing hip joint stability was discovered. This discovery led to the development of a stress-radiographic positioning method to quantitate hip joint laxity in dogs. The method incorporated 2 views with the dog in supine position and hips at neutral flexion/extension angle: a compression view, with the femoral heads fully seated in the acetabula; and a distraction view, with the femoral heads at maximal lateral displacement. An index measurement method was formulated to quantitate the relative degree of joint laxity appearing in either the compression or distraction view. Clinical evaluation of 6 dogs was done to compare the compression/distraction method with the standard hip-extended radiographic method. Also, the stress-radiographic method was performed on 16-week-old Borzoi and German Shepherd Dogs to compare the characteristics of inherent hip joint laxity in these breeds. In all dogs tested, hip joint laxity was masked by the standard hip-extended view as indicated by a 2.5-fold improvement in sensitivity to hip joint laxity of the new method (P less than 0.00001). Moreover, the mean hip joint laxity of 16-week-old German Shepherd Dogs exceeded the mean hip joint laxity of Borzois by 79% (P less than 0.00001). Reports in the literature document the incontrovertible association of hip joint laxity to the development of hip dysplasia in dogs. We believe the ability to accurately quantitate hip joint laxity will provide key diagnostic and prognostic criteria for the selection of pet dogs, and more importantly, breeding stock.     

Measurement of femoral angles in four dog breeds

Objective— To develop a standard method of measurement for femoral angles and report values for normal Labrador Retrievers, Golden Retrievers, German Shepherds, and Rottweilers.
Study Design— Retrospective evaluation of canine pelvis and femoral radiographs.
Sample Population— Radiographs of Labrador Retrievers, Golden Retrievers, German Shepherds, and Rottweilers (n=100 for each breed).
Methods— Anatomic lateral distal and proximal femoral angle, mechanical lateral distal and proximal femoral angle, and femoral angle of inclination were measured from radiographs.
Results— For the 4 breeds (Labrador Retrievers, Golden Retrievers, German Shepherds, and Rottweilers, respectively) anatomic lateral distal femoral angles were 97°, 97°, 94°, and 98°; mechanical lateral distal femoral angles were 100°, 100°, 97°, and 100°; anatomic lateral proximal femoral angles were 103°, 98°, 101°, and 96°; mechanical lateral proximal femoral angles were 100°, 95°, 97°, and 93°; and inclination angles were 134°, 134°, 132°, and 137°. Labrador Retrievers, Golden Retrievers, and Rottweilers had significantly higher values for both anatomic and mechanical lateral distal femoral angle than German Shepherds. Anatomic and mechanical lateral proximal angles were greatest for Labrador Retrievers and lowest for Rottweilers.
Conclusion— Anatomic and mechanical femoral joint angles vary between breeds of dogs.
Clinical Relevance— Values for femoral joint angles may be clinically useful for angular limb deformity diagnosis, treatment, and assessment.     

Distraction index as a risk factor for osteoarthritis associated with hip dysplasia in four large dog breeds*

Objective : To determine if age, breed, gender, weight or distraction index (DI) influenced the risk of radiographic osteoarthritis (OA) of canine hip dysplasia (CHD) in four common dog breeds; the American bulldog, Bernese mountain dog, Newfoundland and standard poodle. Materials and Methods : This was a cross sectional prevalence study with 4349 dogs. Canine hips were evaluated using 3 radiographic projections: the hip-extended view, the compression view and the distraction view. The hip-extended view was examined for the presence of OA. The PennHIP distraction view was utilized to calculate the DI. For all breeds, a multiple logistic regression model incorporating age, weight, gender, and DI was created. For each breed, disease-susceptibility curves grouping dogs on the basis of age were constructed. Receiver-operating characteristic (ROC) curves were developed for each breed regardless of age. Results : For all breeds, DI was the most significant risk factor for the development of OA associated with CHD. Weight and age were also significant risk factors in all four breeds, but gender was not. Clinical Significance : Results from this study support previous findings, that irrespective of breed, the probability of radiographic OA increases with hip joint laxity as measured by the DI. Breed-specific differences in this relationship, however, warrant investigation of all breeds affected by CHD to determine inherent dependency of hip OA on joint laxity. Such findings guide veterinarians in helping dog breeders to make evidence-based breeding decisions and in informing dog owners to implement preventative treatments for CHD for dogs found to be at risk.     

Localized and disseminated histiocytic sarcoma of dendritic cell origin in dogs

Canine histiocytic proliferative disorders include a wide spectrum of diseases characterized by different biologic behaviors. The etiology and pathogenesis of these diseases are largely unknown. The clinicopathologic, morphologic and immunophenotypic characteristics of canine localized and disseminated histiocytic sarcoma were examined in 39 dogs. Rottweilers, Bernese Mountain Dogs, and retrievers were most commonly affected (79%). Localized histiocytic sarcomas (19 dogs) arose from a single site, and metastatic lesions were observed in draining lymph nodes. Predilection sites were subcutis and underlying tissues on extremities, but tumors occurred in other locations, including spleen, lung, brain, nasal cavity, and bone marrow. Disseminated histiocytic sarcomas (20 dogs), a multisystem disease previously described as malignant histiocytosis, primarily affected spleen, lungs, bone marrow, liver, and lymph nodes. Both localized and disseminated canine histiocytic sarcomas were composed of pleomorphic tumor cell populations. CD1+, CD4-, CD11c+, CD11d-, MHC II+, ICAM-1 +, Thy-1 +/- tumor cells were identified in all snap-frozen samples (31 dogs). This phenotype is characteristic for myeloid dendritic antigen-presenting cell lineage. Hence, canine localized and disseminated histiocytic sarcomas are likely myeloid dendritic cell sarcomas. Dendritic antigen-presenting cells are a heterogeneous cell population with regards to their ontogeny, phenotype, function, and localization. The exact sublineage of the proliferating dendritic antigen-presenting cells involved in canine histiocytic sarcomas remains to be determined. Phenotypic analysis of formalin-fixed tissues from eight dogs was limited by available markers. Morphologic features and the phenotype CD18+, CD3-, and CD79a- were the most useful criteria to indicate likely histiocytic origin.     

Phenotypic and genetic evaluation of elbow dysplasia in Dutch Labrador Retrievers, Golden Retrievers, and Bernese Mountain dogs

Canine elbow dysplasia encompasses four developmental diseases: ununited anconeal process, osteochondrosis of the medial part of the humeral condyle, fragmented medial coronoid process (FCP), and incongruity of the elbow joint. Four radiographic views per joint were used to evaluate 2693 Labrador Retrievers (LRs), 1213 Golden Retrievers (GRs), and 974 Bernese Mountain Dogs (BMDs) for the presence of elbow dysplasia between 2002 and 2009 in the Netherlands. The views were also graded for signs of osteoarthritis and sclerosis. FCP was diagnosed most frequently in LRs, GRs and BMDs, with an incidence of 6%, 5%, and 15%, and a heritability of 0.17, 0.24, and 0.06, respectively. Heritabilities were estimated using a sire model and all available ancestors. Sclerosis at the base of the medial coronoid process was the radiographic sign most strongly correlated with FCP (r=0.95, 0.92, and 0.95 in LRs, GRs and BMDs, respectively). The sex of the dog was significantly correlated with the presence of osteoarthritis in LRs, but not in GRs and BMDs. Male LRs were 1.7-fold more frequently, but not more severely, affected by osteoarthritis than female dogs. Age at radiographic examination was significantly associated with osteoarthritis in all three breeds. The heritability estimates in Retrievers were high enough to warrant including FCP findings in the breeding policy, but until the biomechanical and genetic background of elbow dysplasia are better understood, correct phenotyping with a sensitive technique is essential.     

Comparison of two canine registry databases on the prevalence of hip dysplasia by breed and the relationship of dysplasia with body weight and height

OBJECTIVE: To compare the results of 2 canine registries for classification of the hip joints for dysplasia by breed, and to relate the percentage of dysplastic dogs with body metric characteristics. SAMPLE POPULATION: Data on the ranking order of hip dysplasia by breed from 2 registries for 156 dog breeds. PROCEDURES: The prevalence of hip dysplasia listed by the Orthopedic Foundation for Animals (OFA) and the breed mean score according to the list of the British Veterinary Association (BVA) Kennel Club Hip Dysplasia scheme were related to weight and height as well as the body mass index (BMI; kg/m(2)) by breed. RESULTS: The OFA ranking order and the percentage of dysplastic dogs were highly correlated with the BVA mean score (rho = 0.74). A significant correlation was found between the prevalence of hip dysplasia and the BMI (r = 0.63). Receiver operating characteristic curve analysis revealed that the highest area under the curve, corresponding to the best discrimination, was at a BMI of 110 kg/m(2) with a criterion value of 15% dysplastic dogs (area under the curve, 0.89). Because the ratio of dogs in the positive and negative groups reflected the prevalence of the condition among breeds in the OFA database, the positive likelihood ratio was 9.32 and the negative likelihood ratio was 0.24. CONCLUSION AND CLINICAL RELEVANCE: The OFA statistics and the BVA mean scores reflected the prevalence of hip dysplasia among dog breeds. Body mass index accurately discriminated between breeds with high or low prevalence of hip dysplasia.