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.

Comparison of Two Distraction Devices for Assessment of Passive Hip Laxity in Dogs.

Canine hip dysplasia is the most common orthopedic developmental condition in the dog and early hip laxity is the main risk factor. The importance of hip laxity in young animals in the development of hip dysplasia is unanimously recognized among researchers and veterinarians due to its medical applicability in terms of disease control and prevention. In the market, there is some certified hip distractors to promote joint laxity. However, the clinical use of some of these distractors complies with a set of usage rules, that can limit its medical application. In this study was compared the technical quality of radiographs and hip distraction using a certified hip distractor (CertD) and Dis-UTAD in 104 dogs (208 joints). The mean pelvic tilting of 1.5 ± 1.6° and 1.5 ± 1.8° were similar when using the CertD and the Dis-UTAD distractors, respectively (P > 0.05). In the CertD sample, the mean hip distraction index (DI) was 0.46 ± 0.17 and in the Dis-UTAD 0.46 ± 0.16; the mean DI differences was 0.001 ± 0.045, resulting in a non-significant paired t-test (P = 0.65) and a significant intraclass correlation coefficient of 0.96, with the 95% lower limit confidence interval of 0.95 (P < 0.05). The statistical power analysis showed a very low distraction index difference effect size. The results suggest that the statistical reproducibility of CertD hip distraction by the Dis-UTAD and the DI mean differences of 0.001 might be considered without clinical importance. The Dis-UTAD might be considered adequate to promote dog hip laxity.

Distraction index measurement on the dog's hip joint using a dedicated software / [Medição do índice de distração da anca do cão usando um software especial]

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.(AU)

O objetivo deste estudo foi testar a viabilidade de uma nova ferramenta de software informático para avaliação da lassitude articular passiva da articulação coxofemoral. A lassitude articular da articulação coxofemoral foi estimada usando-se um programa informático especial, desenvolvido para o efeito, por dois avaliadores, um com treino prévio e outro não treinado, na medição do índice de distração, em duas sessões independentes, utilizando-se 230 articulações coxofemorais de 115 cães, as quais efetuaram o rastreio de displasia coxofemoral realizando a projeção de distração da articulação coxofemoral. Previamente, todas as radiografias foram enviadas para o PennHIP Analysis Center, para se obter uma medida oficial do índice de distração. A repetibilidade das medições das duas sessões foi adequada para ambos os avaliadores. A reprodutibilidade do índice de distração oficial, média±desvio-padrão 0,44±0,15, foi adequada (P>0,05) para o avaliador treinado, 0,44±0,15, e não adequada (P>0,05) para o avaliador não treinado, 0,47±0,17. A ferramenta de medição do índice de distração proposta pode ser usada com segurança na medição do índice de distração por avaliadores treinados, uma vez que mostra uma adequada repetibilidade e reprodutibilidade das medições oficiais do índice de distração. A simplicidade do processo apresentado torna-o menos demorado e mais econômico.(AU)

Provisional heritability estimates of four distraction index traits in a breeding population of German Shepherd dogs.

AIM To obtain provisional estimates of the heritability (h2 ) of passive laxity of the coxofemoral joints of a breeding colony of German Shepherd dogs, measured using the PennHIP distraction index (DI). METHODS Records were obtained of the PennHIP DI of right and left hips of 195 German Shepherd dogs (377 DI records) from the dog breeding colony of the New Zealand Police Dog Breeding Centre between 2003 and 2016, as well as pedigree records of 884 animals over four generations. Estimates of h2 and variance components for the log transformed DI data were obtained using restricted maximum likelihood procedures with a single trait sire model. Four DI traits for each dog were analysed: left hip, right hip, mean and worse-hip DI. The model included the fixed effects of sex and year of birth, with the age at scoring as a covariable, the random sire effect and residual error for each observation. RESULTS The h2 of the DI of the left hip (0.81, SE 0.40) was higher than the h2 of the DI of the right hip (0.35, SE 0.36). The h2 for the worse-hip DI (0.15, SE 0.28) in each dog was lower than the h2 of the individual hip DI, or the h2 for the mean of the two hips (0.53, SE 0.36) in each dog. The low number of generations prevented a meaningful analysis of the genetic trend. CONCLUSIONS AND CLINICAL RELEVANCE The h2 estimates for the left, right and mean DI traits were moderate to high, whereas the h2 estimates for the worse-hip DI (as used by the PennHIP programme for ranking of dogs) was low, but all estimates had large SE due to the small sample size. This provisional estimate of the h2 of four distraction index traits suggests that the mean DI could be useful as a selection tool against canine hip dysplasia in German Shepherd dogs, whereas the worse-hip DI may be less effective. Heritability estimates from a population with a greater number of DI measures is needed to validate this finding given the large SE in our study.

The Norberg angle is not an accurate predictor of canine hip conformation based on the distraction index and the dorsolateral subluxation score.

Canine hip dysplasia (CHD) is a common complex trait characterized by abnormal hip joint development. Hip joint laxity, an early characteristic of CHD, results in degeneration of the joint due to mechanical trauma, which is a clinical problem mostly in medium to large breed dogs. Clinical signs include pain, decreased activity and lameness. A retrospective, multi-center, cross sectional study of 437 dogs was performed to determine if a Norberg angle (NA) ≥105° accurately predicts a non-dysplastic hip based on a distraction index (DI) cut-off of ≤0.3 or a dorsolateral subluxation (DLS) score cut-off of ≥55%. The predictive capacity of the NA against a DI ≤0.3 or a DLS score ≥55% was assessed using area under the receiver operator characteristic (ROC) curve analysis. The ROC curve of NA for the prediction of a DI ≤0.3 was 0.59 (95% CI=0.50-0.69) and for the prediction of DLS score ≥55% was 0.69 (95% CI=0.63-0.75). Optimizing the specificity of the NA to ≥80% for prediction of a DI ≤0.3 and a DLS score ≥55% gave a cut-point for the NA of ≥112° and 108.7°, respectively. In conclusion, at the cut-point of 105°, the NA is not an accurate measurement to score normal or abnormal hips, based on the DI or DLS score. Application of screening methods for CHD based on hip laxity, such as the DI or the DLS score, would help to remove additional dysplastic dogs from the breeding pool or the NA criterion should be higher when selecting unaffected dogs for breeding.

Morgan line and its relationship with distraction index, angle of inclination and degenerative joint disease in the diagnosis of canine hip dysplasia / Linha Morgan e sua relação com índice de distração, ângulo de inclinação e doença articular degenerativa no diagnóstico da displasia coxofemoral canina

We evaluated 160 hip joint radiographs of 40 dogs of different large breeds (25 females and 15 males) from the metropolitan area of Belo Horizonte, Minas Gerais, Brazil. The radiographs of each dog were obtained at two different stages: stage 1 (mean 7.23 months) and stage 2 (mean 14.25). The conventional radiographic method (CRM) and the radiographic distraction method (RDM) were used, carried out in both stages. CRM measured the Norberg angle (NA), the angle of inclination (AI) and evaluated the presence of degenerative joint disease (DJD). The MRD was performed to establish the distraction index (DI). The aims were to evaluate the presence of the Morgan line and other signs of DJD and correlate them with the degree of canine hip dysplasia (CHD) and also check if the DI greater than 0.3 (first stage) was associated with the presence of ML (second stage). It was found that DI, AI and changes of femoral neck and the formation of osteophytes were associated with the presence of ML. It was observed that if the DI is greater than 0.3 at the first stage, the chance of a positive outcome of ML in the second stage increases by 7.2 times. Thus, 49 joints showed DI > 0.3 at the first stage, in which 31 (63.3 %) presented ML at the second stage. Of the 31 animals that showed DI ≤ 0.3 at first, six (19.4%) had LM at the second stage. There has been a significant association between the presence of ML and the degree of CHD. The more severe the CHD, the higher the percentage of positive ML results. Thus, among the 24 (60 %) animals that showed ML, 11 (45.83 %) were classified as severe dysplastics, 5 (20.83%) as moderate and 8 (33.33 %) as mild. None of the animals classified as normal or borderline presented ML. Among the 8 animals classified as mild dysplastics, 5 showed only ML as DJD.(AU)

Avaliaram-se 160 radiografias das articulações coxofemorais de 40 cães de diferentes raças de grande porte, provenientes de Belo Horizonte, Brasil. As radiografias de cada animal foram obtidas em dois momentos: um (média de 7,23 meses de idade) e dois (média de 14,25 meses). Utilizaram-se o método radiográfico convencional (MRC) e o método radiográfico em distração (MRD), ambos realizados nos dois momentos. No MRC, mensurou-se o ângulo de Norberg (AN), o ângulo de inclinação (AI) e avaliou-se a presença de doença articular degenerativa (DAD). O MRD foi realizado para se estabelecer o índice de distração (ID). Os objetivos foram avaliar a presença da linha Morgan (LM) e de outros sinais de DAD, correlacionando-os com o grau de displasia coxofemoral (DCF); além de se verificar se o ID maior que 0,3 (primeiro momento) possui associação com a presença de LM (segundo momento). Verificou-se que ID, AI e encurtamento e/ou espessamento do colo femoral e formação de osteófitos foram associados à presença da LM. Observou-se que, quando o ID era maior que 0,3 no primeiro momento, a chance de um resultado positivo da LM no segundo momento aumentava em 7,2 vezes. No primeiro momento, 49 articulações apresentaram ID > 0,3. Destas, 31 (63,3%) apresentaram LM no segundo momento. Dos 31 animais que apresentaram ID ≤ 0,3 no primeiro momento, seis (19,4%) desenvolveram LM no segundo momento. Houve associação significativa entre presença de LM com o grau de DCF, e quanto mais grave a DCF, maior foi o percentual de resultados positivos da LM. Dos 24 (60%) animais que apresentaram LM, 11 (45,83%) foram classificados como displásicos graves, cinco (20,83%) como médios e oito (33,33%) como leves. Nenhum dos animais considerados suspeitos ou normais apresentou LM. Dos oito animais classificados como displásicos leves, cinco apresentaram apenas LM como sinal de DAD.(AU)

Avaliação radiográfica da diplasia coxofemoral de cães adultos: comparação entre dois métodos / Evaluation of radiographic hip dysplasia in adult dogs: comparison between two methods

O objetivo deste estudo foi comparar a eficiência dos métodos radiográficos convencional e em distração de cães da raça Pastor Alemão adultos. Foram utilizados 16 animais, sendo onze fêmeas e oito machos, com idade média de quatro anos e dez meses. Todos os cães participantes foram avaliados clinicamente para se detectar a presença de alterações relacionadas ao aparelho locomotor e/ou sistema nervoso que afetariam a locomoção normal do cão, excluindo-se as alterações clínicas decorrentes do quadro de displasia coxofemoral (DCF). Para avaliação radiográfica das articulações coxofemorais, foram realizadas duas técnicas de avaliação, o Método Radiográfico Convencional (MRC), adotado pela Fédération Cynologique Internationale, e o Método Radiográfico em Distração (MRD). Dos animais avaliados, 62,5% foram classificados com algum grau de DCF. A correlação entre o MRC e o MRD foi moderada e a utilização isolada do MRD, pouco eficaz, com sensibilidade de 75% e especificidade de 44%. Nas condições em que este experimento foi conduzido, pode-se concluir que o MRC é um exame eficaz no diagnóstico quando comparado ao MRD em cães da raça Pastor Alemão adultos...

The aim of this study was to compare the efficacy of conventional and distraction radiographic methods in adult German Shepherd dogs. Sixteen animals were tested, eleven females and eight males, with a mean age of 4.8 years. All dogs were clinically evaluated to detect locomotor and/or nervous system changes that could affect normal locomotion, but clinical hip dysplasia (HD) alterations were excluded. Two techniques were used for radiographic evaluation of hip joints, the Conventional Radiographic Method (CRM), adopted by Fédération Cynologique Internationale and the Distraction Radiographic Method (DRM). 62.5% of the evaluated animals were classified as having some degree of HD. The correlation between CRM and DRM was moderate. When DRM was used alone, it was considered an ineffective method, with 75% sensitivity and 44% specificity. From this study, it can be concluded that CRM is an effective diagnostic method for hip dysplasia when compared to DRM in adult German Shepherd dogs...