Early hip laxity examination in predicting moderate and severe hip dysplasia in Estrela mountain dog

Mechanical osteoarthritis of the hip in a one medicine concept: a narrative review

Human and veterinary medicine have historically presented many medical areas of potential synergy and convergence. Mechanical osteoarthritis (MOA) is characterized by a gradual complex imbalance between cartilage production, loss, and derangement. Any joint instability that results in an abnormal overload of the joint surface can trigger MOA. As MOA has a prevailing mechanical aetiology, treatment effectiveness can only be accomplished if altered joint mechanics and mechanosensitive pathways are normalized and restored. Otherwise, the inflammatory cascade of osteoarthritis will be initiated, and the changes may become irreversible. The management of the disease using non-steroidal anti-inflammatory drugs, analgesics, physical therapy, diet changes, or nutraceuticals is conservative and less effective. MOA is a determinant factor for the development of hip dysplasia in both humans and dogs. Hip dysplasia is a hereditary disease with a high incidence and, therefore, of great clinical importance due to the associated discomfort and significant functional limitations. Furthermore, on account of analogous human and canine hip dysplasia disease and under the One Medicine concept, unifying veterinary and human research could improve the well-being and health of both species, increasing the acknowledgement of shared diseases. Great success has been accomplished in humans regarding preventive conservative management of hip dysplasia and following One Medicine concept, similar measures would benefit dogs. Moreover, animal models have long been used to better understand the different diseases' mechanisms. Current research in animal models was addressed and the role of rabbit models in pathophysiologic studies and of the dog as a spontaneous animal model were highlighted, denoting the inexistence of rabbit functional models to investigate therapeutic approaches in hip MOA.

Femoral Neck Thickness Index as an Indicator of Proximal Femur Bone Modeling

The alteration in the shape of the femoral neck is an important radiographic sign for scoring canine hip dysplasia (CHD). Previous studies have reported that the femoral neck thickness (FNT) is greater in dogs with hip joint dysplasia, becoming progressively thicker with disease severity. The main objective of this work was to describe a femoral neck thickness index (FNTi) to quantify FNT and to study its association with the degree of CHD using the Fédération Cynologique Internationale (FCI) scheme. A total of 53 dogs (106 hips) were randomly selected for this study. Two examiners performed FNTi estimation to study intra- and inter-examiner reliability and agreement. The paired t-test, the Bland-Altman plots, and the intraclass correlation coefficient showed excellent agreement and reliability between the measurements of the two examiners and the examiners' sessions. All joints were scored in five categories by an experienced examiner according to FCI criteria. The results from examiner 1 were compared between FCI categories. Hips that were assigned an FCI grade of A (n = 19), B (n = 23), C (n = 24), D (n = 24), and E (n = 16) had a mean ± standard deviation FNTi of 0.809 ± 0.024, 0.835 ± 0.044, 0.868 ± 0.022, 0.903 ± 0.033, and 0.923 ± 0.068, respectively (ANOVA, p < 0.05). Therefore, these results show that FNTi is a parameter capable of evaluating proximal femur bone modeling and that it has the potential to enrich conventional CHD scoring criteria if incorporated into a computer-aided diagnosis capable of detecting CHD.

Radiographic Diagnosis of Hip Laxity in Rottweilers: Interobserver Agreement at Eight- and Twelve-Months of Age

Hip laxity is one of the predisposing factors of canine hip dysplasia. The early diagnosis of hip laxity allows veterinarians to prevent the participation of dysplastic dogs in breeding programs, which could lower the disease's prevalence due to its genetic background. Furthermore, it allows them to plan preventive/therapeutic procedures for mild/near-normal hips to reduce the symptoms of the disease at older ages. A reliable screening program must be repeatable and reproducible, and intra- and inter-observer studies can help us to determine the best methods. In this study, we aimed to evaluate the radiographic parameters used for the early diagnosis of hip dysplasia in Rottweilers at 8 and 12 months of age with five observers to assess the interobserver agreements. According to our findings, there were high interobserver agreements at both ages for the quantitative values, such as the center edge angle (CEA), dorsal acetabular rim slope (DARS), distraction index (DI), and Norberg angle (NA), whereas we recorded from poor to moderate agreements for the qualitative values, such as the grading of the dorsal acetabular rim (GDAR), grading of the degenerative joint disease (GDJD), location of the center of the femoral head (LCFH), and sclerosis of the cranial acetabular rim (SCAR).

Acetabular rim extension using a personalized titanium implant for treatment of hip dysplasia in dogs: short-term results

Hip dysplasia (HD) is a common orthopedic problem in young dogs. To decrease the laxity of the hip joint related to HD, the surgical treatments are recommended to increase femoral head coverage. ACEtabular rim eXtension (ACE-X) using a personalized 3-dimensional printed titanium shelf implant is a new surgical treatment to increase femoral head coverage and decrease laxity of the dysplastic hip joint, however, the efficacy is less know. Client-owned dogs older than 6 months with clinical signs of coxofemoral joint subluxation and radiographic evidence of HD with no or mild osteoarthritis (OA) were included. The Norberg angle (NA), linear percentage of femoral head overlap (LFO), and percentage of femoral head coverage (PC) were investigated radiographically and with computed tomography (CT) before and after surgery. OA was graded (scores 0-3) according to the maximum osteophyte size measured on CT. In addition, joint laxity (Ortolani) test results, gait analysis, and the Helsinki chronic pain index (HCPI) questionnaire were obtained at preoperative, immediately postoperative and at 1.5- and 3-month evaluations. Acetabular rim extension was performed in 61 hips of 34 dogs; NA, LFO, and PC were significantly higher immediately postoperatively and at the 1.5- and 3-month follow-up examinations compared with preoperative values (p < 0.05). Osteophyte size gradually increased over time (p < 0.05). The OA score significantly increased between preoperatively and directly postoperatively, and between preoperatively and at 3-month follow-up (p < 0.05). The laxity test normalized in 59 out of 61 hips after surgery, and the HCPI questionnaire showed that the pain score decreased significantly at 1.5 and 3 months, postoperatively. The force plate showed no significant improvement during the 3 months follow-up. Although pain reduction by the implant was unclear in short-term results, a personalized shelf implant significantly increased femoral head coverage and eliminated subluxation of the dysplastic hip joint. Further studies are required to study the long-term efficacy of gait, chronic pain, and progression of osteoarthritis.

Inter-Observer Agreement in Radiographic Diagnosis of Coxofemoral Joint Disease in a Closed Cohort of Four-Month-Old Rottweilers

Canine hip dysplasia is a complex and multifactorial disease. The early diagnosis of dysplastic dogs under one year of age helps veterinarians to plan proper preventive/therapeutic methods. Having an accurate screening method increases the chance of the early detection of dysplasia. The goal of our study was to assess the inter-observer reliability of eight radiographic parameters in four-month-old Rottweilers. Radiographs of the 28 Rottweilers were investigated by five experienced observers. The radiographs were taken in ventrodorsal view with extended legs, frog-leg ventrodorsal view, distraction view, and dorsal acetabular rim view. Four quantitative parameters such as Norberg angle (NA), distraction index (DI), dorsal acetabular rim slope (DARS), and center edge angle (CEA) and four qualitative parameters such as sclerosis of the cranial acetabular rim (SCAR), location of the center of the femoral head (LCFH), grading of the degenerative joint disease (GDJD), and grading of the dorsal acetabular rim (GDAR) were evaluated. High inter-observer agreements were recorded for quantitative values, whereas the inter-observer agreement of the qualitative parameters was low. It can be deduced that the evaluated quantitative parameters are reliable, and a combination of these methods with clinical examinations might increase the accuracy of the examinations.

Early hip laxity screening and later canine hip dysplasia development

Background and Aim:

Passive hip laxity (PHL) is considered the primary risk factor for canine hip dysplasia (HD) and is estimated, in stress hip radiographs, using the distraction index (DI). The study aimed to associate the early PHL using the hip Distractor of University of Trás-os-Montes and Alto Douro (DisUTAD) and the late HD grades.

Materials and Methods:

A total of 41 dogs (82 hips) were submitted to a follow-up study. First, between 4 and 12 months of age, dogs were radiographed using the DisUTAD hip distractor and were determined the DI for each hip joint. Then, after 12 months of age, dogs were reevaluated for HD using the conventional hip ventrodorsal projection and hips were evaluated for HD using the Fédération Cynologique Internationale (FCI) scoring system.

Results:

Hips of dogs’ in the second examination with FCI grades of A (n=28), B (n=11), C (n=22), and D and E (n=21) had an early DI of 0.32±0.1, 0.38±0.08, 0.50±0.12, and 0.64±0.11, respectively. Statistical analysis using the general linear model univariate, with the DI as dependent variable and the FCI grades, side and sex as fixed factors, and the post hoc Bonferroni correction test showed significant differences among FCI grades (p<0.05).

Conclusion:

These results show the association between early DI and the late FCI HD grades and the DisUTAD is recommended for the early canine HD diagnosis.

Patient-specific 3D-printed shelf implant for the treatment of hip dysplasia tested in an experimental animal pilot in canines

The concept of a novel patient-specific 3D-printed shelf implant should be evaluated in a relevant large animal model with hip dysplasia. Therefore, three dogs with radiographic bilateral hip dysplasia and a positive subluxation test underwent unilateral acetabular augmentation with a 3D-printed dog-specific titanium implant. The contralateral side served as control. The implants were designed on CT-based pelvic bone segmentations and extended the dysplastic acetabular rim to increase the weight bearing surface without impairing the range of motion. Outcome was assessed by clinical observation, manual subluxation testing, radiography, CT, and gait analysis from 6 weeks preoperatively until termination at 26 weeks postoperatively. Thereafter, all hip joints underwent histopathological examination. The implantation and recovery from surgery was uneventful. Clinical subluxation tests at the intervention side became negative. Imaging showed medialization of the femoral head at the intervention side and the mean (range) CE-angle increased from 94° (84°-99°) preoperative to 119° (117°-120°) postoperative. Gait analysis parameters returned to pre-operative levels after an average follow-up of 6 weeks. Histology showed a thickened synovial capsule between the implant and the femoral head without any evidence of additional damage to the articular cartilage compared to the control side. The surgical implantation of the 3D shelf was safe and feasible. The patient-specific 3D-printed shelf implants restored the femoral head coverage and stability of dysplastic hips without complications. The presented approach holds promise to treat residual hip dysplasia justifying future veterinary clinical trials to establish clinical effectiveness in a larger cohort to prepare for translation to human clinic.

Imaging diagnosis of canine hip dysplasia with and without human exposure to ionizing radiation

Hip dysplasia (HD) is one of the most common hereditary orthopaedic diseases in dogs, with serious implications for the quality of life of the affected animals. Radiographic screening is essential for the selection of breeding stock in some at-risk breeds, and radiography is also used in the diagnosis of clinical HD cases. A definitive diagnosis of HD is based on radiographic examination, and the most commonly used view is the ventrodorsal hip extended projection, sometimes in combination with various hip stress-based techniques. Radiographic images require high quality positioning and dogs are usually anesthetized and often manually restrained to facilitate optimal positioning. The 'as low as reasonably achievable' (ALARA) principle used in human radioprotection is not always fulfilled in veterinary practice, except in the UK, where human exposure to ionizing radiation in veterinary medicine is strictly regulated. While each dose of ionizing radiation is small, doses accumulate over a lifetime, which can eventually result in substantial radiation exposure. Therefore, manual restraint should be avoided and mechanical immobilization, sedation or general anaesthesia should be used. This review examines the biological effects of human exposure to ionizing radiation and common sources of veterinary exposure. The diagnostic quality of imaging methods for the diagnosis of canine HD is compared between manually restrained and hands-free dog positioning. Hands-free radiographic techniques are available to assess hip laxity, degenerative joint changes and hip osseous structure while preserving image quality, and can be used to select animals for breeding or for the diagnosis of HD.

Early Diagnosis of Canine Hip Laxity: Correlation between Clinical Orthopedic Examinations and the FCI Scoring Method in a Closed Cohort of Rottweilers

Simple Summary

Canine hip dysplasia is one of the most frequently occurring orthopedic diseases in dogs, and hip laxity is the primary sign of this disease. The early diagnosis of hip laxity in puppies would make veterinarians capable of planning preventative procedures to treat the disease or reduce the severity of disease at older ages. These procedures would improve the quality of the life of the dogs and reduce treatment costs. Furthermore, because of the importance of genetics in this disease, dogs with a risk of developing canine hip dysplasia in the future could be excluded from breeding programs. Therefore, the early diagnosis of canine hip laxity, as well as the selection of proper diagnostic methods, are of great importance in small animal orthopedics.

Abstract

Canine hip dysplasia is a multifactorial disorder characterized by hip laxity and osteoarthritis. The early diagnosis of hip laxity is an important topic in small animal orthopedics. This study aimed to evaluate the correlation between clinical orthopedic examinations and the Fédération Cynologique Internationale (FCI) scoring method. Thirty purebred Rottweilers were examined at approximately four (20 ± 2 weeks), eight (35 ± 2 weeks), and twelve months of age (54 ± 1 weeks), respectively. The Ortolani, Barlow, and Bardens tests and reduction/subluxation angle measurements were performed at each time. FCI scoring was conducted at the third examination time. Positive correlations were recorded between the reduction angle and Ortolani test, reduction angle and FCI score, and Ortolani test and FCI score for the second and third examination dates. No correlation was observed between the subluxation angle and other methods. Despite previous studies reporting 16–20 weeks as the earliest age for diagnosing hip laxity in dogs, in our study, early diagnosis was possible from the age of 35 ± 2 weeks. This difference might originate from the small sample size, low number of the dogs with severe grades of laxity, and breed differences.

Effectiveness of PennHIP and Orthopedic Foundation for Animals measurements of hip joint quality for breeding selection to reduce hip dysplasia in a population of purpose-bred detection dogs

OBJECTIVE

To examine the effectiveness of applying selective pressure to improve hip joint quality in purpose-bred detection dogs by use of PennHIP distraction index (DI) values along with Orthopedic Foundation for Animals (OFA) hip joint scores and to determine whether age, sex, coat color, breed, and body weight were associated with hip joint quality.

ANIMALS

615 purpose-bred detection dogs assessed for hip joint quality.

PROCEDURES

Orthopedic records of 615 purpose-bred detection dogs (569 Labrador Retrievers and 46 Labrador Retriever-German Wirehaired Pointer crossbred dogs) from 2000 through 2017 were analyzed. From 2000 to 2014, hip joint quality scores were determined by OFA evaluation only (429 dogs). Beginning in 2015, both PennHIP and OFA evaluations were used to select male and female breeding stock (179 dogs; 7 dogs were removed from analysis because they did not undergo both evaluations). Selection threshold DI value for sires and dams was ≤ 0.30; all had hip joint scores of excellent or good by OFA standards. Standard ventrodorsal hip joint-extended and stress (compression and distraction) pelvic radiographs were submitted for OFA and PennHIP evaluations.

RESULTS

Hip joint quality scores were unchanged by use of OFA measurements only. When both PennHIP and OFA measurements were used for the selection of breeding stock, hip joint quality scores improved significantly. Sex and age were significant predictors of DI values.

CONCLUSIONS AND CLINICAL RELEVANCE

PennHIP DI values were an effective measurement of hip joint quality for selecting breeding stock, and the addition of DI values to OFA measurements significantly improved hip joint quality in a population of purpose-bred dogs.

Distraction index measurement on the dog's hip joint using a dedicated software

ABSTRACT The aim of this study was to test the accuracy of a new automated computer software tool for the assessment of passive hip laxity. The hip laxity was estimated using the dedicated computer software by two blinded evaluators, one previously trained and one without specific training for distraction index measurement, in two independent sessions using 230 hip joints from 115 dogs that underwent screening for passive hip laxity using the distraction view. Previously, all of these radiographs were sent to PennHIP Analysis Center for an official distraction index record. The measurement repeatability of the two sessions was adequate for both evaluators. The reproducibility of the official distraction index measurement, mean distraction index±standard deviation 0.44±0.15, was adequate (P>0.05) for the trained evaluator, 0.44±0.15, and non-adequate (P<0.05), for the non-trained evaluator 0.47±0.17. The distraction index measurement tool proposed can be used with confidence for hip laxity evaluation by trained evaluators, as it provided good repeatability and reproducibility of official reports. The simplicity of the process described leads to a less time-consuming and more affordable procedure.

Canine hip dysplasia screening: Comparison of early evaluation to final grading in 231 dogs with Fédération Cynologique Internationale A and B

OBJECTIVES

This study aimed to verify if a significant difference exists between parameters in the early evaluation of normal and near-normal hip joints, to evaluate the influence of age and breed on the parameters, and to clarify the usefulness of a total score for differentiating between Fédération Cynologique Internationale (FCI) grade A and B hips.

METHODS

A total of 231 dogs were classified according to whether they had FCI A or B hips at adulthood, with measurements obtained at 14-28 weeks of age. The total score was calculated by the summation of the following quantitative parameters: angle of subluxation (AS), angle of reduction (AR), laxity index (LI), and dorsal acetabular rim slope (DARS). Logistic regression analysis was performed to establish the probability of the study population to develop an FCI B hip based on the total score. This was repeated for the highest score in combination with the worst-rated hip and once more for breeds.

RESULTS

No correlation between age and the parameters was found in the cohort, or for FCI A and B. The values of all the parameters were significantly lower in the FCI A group than in the FCI B group (AR: 4.42° ± 6.0° vs 7.62° ± 7.2°; AS: 0.45° ± 1.9° vs 1.55° ± 3.8°; LI: 0.32 ± 0.1 vs 0.36 ± 0.1; DARS: 3.30° ± 1.8° vs 3.77° ± 1.9°; TS: 11.47 ± 8.3 vs 16.65 ± 10.9). Labrador Retrievers and Golden Retrievers showed significant differences between parameters for both FCI grades. The range, where FCI A and B hips can be predicted on the basis of the total score, was different when assessed for the entire cohort, Labrador Retrievers, and Golden Retrievers.

CLINICAL SIGNIFICANCE

Our results show that even in normal and near-normal hips, the parameters significantly differed in the early evaluation. Moreover, cutoff values should be set for different breeds in the prediction of the FCI grade during early evaluation for a better breeding selection regarding canine hip dysplasia, one of the most common orthopedic diseases among large and giant breed dogs.

Health problems of Iraqi police dogs referred to Baghdad Veterinary Hospital during 2015-2017

Background and Aim:

Police dogs in Iraq have been working mostly as explosive detectors since 2003. The health problems of these dogs are unique and have not been reported in literature. This investigation assessed the prevalence of health problems in Police dogs referred to Baghdad Veterinary Hospital during 2015-2017.

Materials and Methods:

A total of 1220 police dogs that were referred to Baghdad Veterinary Hospital in 2015-2017 were studied. The dogs were mostly German Shepherd dogs (GSDs) or Belgian Malinois (BM), with an average age of 4.6 years. The dogs’ health problems and some of their risk factors were studied.

Results:

Congestive heart failure (CHF), babesiosis, various malignancies, and intestinal parasites were the most commonly diagnosed health problems, followed by general aging, bronchopneumonia, otitis, nutritional deficiencies, and anemia. GSDs were more prone to CHF, while BM had more diagnoses of malignancies. Age was associated with both health conditions.

Conclusion:

The presence of health problems in these working dogs highlights the need for a stricter and more organized preventive schedule to keep the dogs healthy and efficient at old age.

Protein biomarkers in serum and urine for determining presence or absence of hip dysplasia in a canine model

This study compares serum and urine concentrations of relevant protein biomarkers among adult dogs with or without radiographic canine hip dysplasia (CHD). Adult (≥2 years of age), client-owned dogs (n = 74) radiographically categorized as having at least "good" hips (n = 49) or having "mild," "moderate," or "severe" hip dysplasia (n = 25) by the Orthopedic Foundation for Animals (OFA). Urine and serum samples were obtained from each dog at a single time-point and processed and analyzed for relevant protein biomarkers. Urinary concentrations of CTX-II (p < 0.001) and TIMP-1 (p = 0.002) were significantly lower in dogs with CHD compared to dogs with no CHD. ROC curve analyses were successful in establishing a panel of four biomarkers (urinary CTX-I and II, serum MMP-9, and serum PIICP) with high discriminatory capability for the presence or absence of hip dysplasia in adult dogs (AUC = 0.89). Urine and serum biomarkers can distinguish adult dogs with radiographic CHD from those with no CHD with a sensitivity of 0.95 and specificity of 0.77 using ROC analysis with AUC 0.89. Clinical Significance: This finding suggests that this simple, minimally invasive diagnostic technique has potential for discriminating dysplastic dogs from dogs with normal hips, with possible translational application to humans based on similar etiopathogenesis. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 9999:1-5, 2019.

Emerging insights into the genetic basis of canine hip dysplasia

Canine hip dysplasia (CHD) is the most common inherited polygenic orthopedic trait in dogs with the phenotype influenced also by environmental factors. This trait was described in the dog in 1935 and leads to a debilitating secondary hip osteoarthritis. The diagnosis is confirmed radiographically by evaluating signs of degenerative joint disease, incongruence, and/or passive hip joint laxity. There is no ideal medical or surgical treatment so prevention based on controlled breeding is the optimal approach. The definitive CHD diagnosis based on radiographic examination involves the exposure to ionizing radiation under general anesthesia or heavy sedation but the image does not reveal the underlying genetic quality of the dog. Phenotypic expression of CHD is modified by environmental factors and dogs with a normal phenotype can be carriers of some mutations and transmit these genes to their offspring. Programs based on selection of dogs with better individual phenotypes for breeding are effective when strictly applied but remain inferior to the selection of dogs based on estimation of breeding values. Molecular studies for dissecting the genetic basis of CHD are ongoing, but progress has been slow. In the future, the recommended method to improve hip quality in controlled breeding schemes, which will allow higher selection pressure, would be based on the estimation of the genomic breeding value. Since 2012, a commercial DNA test has been available for Labrador Retrievers using a blood sample and provides a probability for development of CHD but we await evidence that this test reduces the incidence or severity of CHD.

Morphometric assessment of the hip joint in the Estrela Mountain Dog breed

OBJECTIVES

To study the radiographic projected hip parameters of the proximal femur and acetabulum in young and adult Estrela Mountain Dogs with normal and abnormal hip joints. The parameters evaluated were: femoral angles of inclination and anteversion (FAI and FAA), femoral neck length and width (FNL and FNW), acetabular depth (AD) and acetabular angle of retrotorsion (AAR).

METHODS

Five hundred and twenty-five standard hip-extended ventrodorsal radiographic views and 622 mediolateral views of the right and left femur were used to measure the FAI, FAA, FNL, FNW, AD, AAR and modified AAR (mAAR).

RESULTS

The FAI decreased in adult dysplastic dogs, in females and in right femora; FAA decreased with age; FNL was characterized by a greater relative size in normal adult animals; FNW was greater in abnormal hips in young and adult animals; AD was less in adult dysplastic dogs and in right hips; AAR was similar in the studied groups; mAAR was greater in abnormal hips and in left hips.

CLINICAL SIGNIFICANCE

The data may be used in future studies, which compare this breed to others. Morphological variations in femoral neck and acetabular morphometric parameters were present, and these variables in dogs with different ages and with hips in varying states of health should not be compared.

Retrospective analysis for genetic improvement of hip joints of cohort labrador retrievers in the United States: 1970-2007

Background

Canine Hip Dysplasia (CHD) is a common inherited disease that affects dog wellbeing and causes a heavy financial and emotional burden to dog owners and breeders due to secondary hip osteoarthritis. The Orthopedic Foundation for Animals (OFA) initiated a program in the 1960's to radiograph hip and elbow joints and release the OFA scores to the public for breeding dogs against CHD. Over last four decades, more than one million radiographic scores have been released.

Methodology/Principal Findings

The pedigrees in the OFA database consisted of 258,851 Labrador retrievers, the major breed scored by the OFA (25% of total records). Of these, 154,352 dogs had an OFA hip score reported between 1970 and 2007. The rest of the dogs (104,499) were the ancestors of the 154,352 dogs to link the pedigree relationships. The OFA hip score is based on a 7-point scale with the best ranked as 1 (excellent) and the worst hip dysplasia as 7. A mixed linear model was used to estimate the effects of age, sex, and test year period and to predict the breeding value for each dog. Additive genetic and residual variances were estimated using the average information restricted maximum likelihood procedure. The analysis also provided an inbreeding coefficient for each dog. The hip scores averaged 1.93 (±SD = 0.59) and the heritability was 0.21. A steady genetic improvement has accrued over the four decades. The breeding values decreased (improved) linearly. By the end of 2005, the total genetic improvement was 0.1 units, which is equivalent to 17% of the total phenotypic standard deviation.

Conclusion/Significance

A steady genetic improvement has been achieved through the selection based on the raw phenotype released by the OFA. As the heritability of the hip score was on the low end (0.21) of reported ranges, we propose that selection based on breeding values will result in more rapid genetic improvement than breeding based on phenotypic selection alone.

Diagnosis, genetic control and preventive management of canine hip dysplasia: a review

Despite expensive screening and breeding programmes, hip dysplasia (HD) continues to be one of the most common orthopaedic diseases in dogs. The vast majority of dogs afflicted with HD show minimal to no clinical signs, but it can also be a highly debilitating condition for both working and pet dogs. Hip joint laxity is considered a major risk factor for the development of degenerative joint disease and a definitive diagnosis is made if characteristic signs are evident on a ventrodorsal view of the pelvis. Early prediction of the condition can be made using stress radiographic techniques to evaluate the passive hip laxity. The diagnosis of HD may be used for the purpose of selecting breeding stock or to decide on the best treatment approach. Breeding programmes based on individual dog phenotypes have been ineffective and a selection procedure based on breeding value (BV) estimation is recommended. Traditional conservative and surgical treatment approaches are reserved for dogs with overt clinical signs of the disease but such treatments can be expensive and aggressive, and are often ineffective in eliminating clinical signs or subluxation and in preventing the development of degenerative joint disease. The implementation of breeding programmes based on BVs and further research into early prediction/diagnosis of HD and effective preventive treatment approaches are essential.

Passive hip laxity in Estrela Mountain Dog--distraction index, heritability and breeding values

Two hundred and fifteen Estrela Mountain Dogs (EMD) were examined using the PennHIP method between 2002 and 2006. Passive hip laxity (PHL) was estimated calculating the distraction index (DI). Pedigree information was obtained from the Portuguese Kennel Club. The heritability and breeding values were estimated using the linear Animal Model. The DI, using as reference the worst joint of each animal, ranged from 0.15 to 1.12 (0.55 +/- 0.19). The PHL was equal in right and left sides, and was higher in females than in males (P > 0.05 and P <0.01 in the t-test, respectively). The estimated heritability was 0.83 +/- 0.11. The mean breeding values for PHL were stable in EMD born between 1991 and 2003, and showed an improvement in 2004 and 2005. The data confirm high PHL in breeds with high prevalence and severity of canine hip dysplasia. The high heritability indicates that the DI could be reduced in the breed if PHL were used as a selection criterion. The early favourable evolution of DI breeding values could be related with the increase of voluntary radiographic hip screening in the last years, and the subsequent introduction of hip quality as a breeding criterion.

Hip dysplasia in Estrela mountain dogs: prevalence and genetic trends 1991-2005

Three hundred and thirteen Estrela mountain dogs were examined for hip dysplasia (HD) using the standard ventrodorsal hip extended view, and graded into five categories (A, B, C, D and E) using the Fédération Cynologique Internationale's (FCI) scoring system. The Ortolani method was performed to evaluate hip joint laxity. Pedigree information was obtained from the Portuguese Kennel Club and the genetic trend was evaluated by calculating the mean breeding values (BVs) for the last 15 years, using the threshold model. HD was found in 66% of the dogs. There was low-moderate correlation between the results of the Ortolani test and FCI hip scores (r(s)=0.386; P<0.001). Grades of hip dysplasia were equal in both males and females (P=0.14) and in the animals' right and left sides (P=0.51). The mean BVs for HD were stable in dogs born between 1991 and 2003, and showed an improvement in 2004 and 2005. The data confirm the high prevalence and severity of HD in predisposed breeds that do not have breeding programmes in place. It also confirms an initial favourable change in BVs that is a likely consequence of the voluntary radiographic hip-screening programme.