Genetic analysis of three different classification protocols for the evaluation of elbow dysplasia in German shepherd dogs

OBJECTIVES: Three different scoring systems for elbow dysplasia and its radiographic signs were genetically evaluated in 2645 German shepherd dogs. METHODS: An animal model was used to estimate heritabilities and additive genetic and residual correlations for the three scoring systems: ED-SV, which is recommended by the International Elbow Working Group; ED-LA, developed by Lang and others; and ED-TH, proposed by Tellhelm. RESULTS: The effects of sex, age at examination and the correlation between the two factors were significant for all three scoring systems. Heritability estimates (se) were 0.18 (0.04) for ED-SV, 0.11 (0.03) for ED-LA and 0.16 (0.04) for ED-TH. The additive genetic correlations among the different single criteria for elbow dysplasia and the different elbow dysplasia scores were between 0.68 and 0.98, except for the criteria ununited anconeal process and osteochondrosis dissecans of the trochlea humeri, which were mostly genetically negatively correlated to the other radiological criteria. CLINICAL SIGNIFICANCE: The elbow dysplasia scores were determined by two genetically different traits. The possibilities for selecting German shepherd dogs with respect to elbow dysplasia might be improved by taking into account these two traits in the prediction of breeding values.     

Genetic analyses of elbow and hip dysplasia in the German shepherd dog

Results from radiographic screening for canine hip dysplasia (CHD) and elbow dysplasia (CED) of 48 367 German shepherd dogs born in 2001–07 were used for the population genetic analyses. Available information included CHD scores for 47 730 dogs, CED scores for 28 011 dogs and detailed veterinary diagnoses of primary ED lesions for a subsample of 18 899 dogs. Quasi‐continuous traits were CHD, CED and cases of CED without radiographically visible primary lesion (CED‐ARTH). Binary coding was used for fragmented medial coronoid process of the ulna (FCP), borderline findings and mild to severe signs of dysplasia in hip and elbow joints. Genetic parameters were estimated in univariate threshold and multivariate linear and mixed linear‐threshold models using Gibbs sampling. Correlations between univariately predicted breeding values (BV) indicated genetic differences between borderline and affected disease status for both CHD (r_BV = 0.5) and CED (r_BV = 0.3). Multivariate genetic analyses with separate consideration of borderline findings revealed moderate heritabilities of 0.2–0.3 for the quasi‐continuous traits with positive additive genetic correlation of 0.3 between CHD and both CED and CED‐ARTH. For FCP, heritability of 0.6 and additive genetic correlations of +0.1 to CHD and ?0.1 to CED‐ARTH were estimated. Results supported the relevant genetic determination of CHD and CED, argued for both diseases against interpretation of borderline findings as healthy and implied genetic heterogeneity of CED. Accordingly, future breeding strategies to reduce the prevalences of CHD and CED in the German shepherd dog should be most efficient when based on BV from multivariate genetic evaluation for CHD, CED‐ARTH and FCP with use of the whole scale of categories for classification of CHD and CED.     

Prevalence and co-occurrence of hip dysplasia and elbow dysplasia in Dutch pure-bred dogs

Hip as well as elbow dysplasia (HD, ED) are developmental disorders leading to malformation of their respective joints. For a long time both disorders have been scored and targeted for improvement using selective breeding in several Dutch dog populations. In this paper all scores for both HD and ED, given to pure bred dogs in the Netherlands from 2002 to 2010, were analyzed. Heritabilities and correlations between HD and ED were calculated for the 4 most frequently scored breeds. Heritabilities ranged from 0.0 to 0.37 for HD related traits (FCI-score, osteoarthritis, congruity, shape and laxity (Norberg angle); FCI: Fédération Cynologique Internationale) and from 0.0 to 0.39 for ED related traits (IEWG score, osteoarthritis, sclerosis and indentation; IEWG: International Elbow Working Group). HD related traits showed high genetic and residual correlations among each other but were only to a minor extent correlated with ED related traits, which also showed high correlations among each other. Genetic correlations were higher than residual correlations. Phenotypic and genetic trends since 2001 for the four most scored breeds were slightly positive but decreasing over time, indicating that selection over the past decade has not been effective.     

Multivariate genetic analysis of canine hip and elbow dysplasia as well as humeral osteochondrosis in the Bernese mountain dog

In the present study genetic parameters for canine hip dysplasia (CHD), canine elbow dysplasia (CED) and osteochondrosis dissecans of the humeral head (OCD) were analysed in Bernese mountain dogs. The data set included the official scores for CHD and CED from 5534 Bernese mountain dogs born in the years 1995-2008. A multivariate linear animal model was employed to estimate heritabilities, additive genetic and residual correlations using residual maximum likelihood (REML). Heritability estimates were h2 = 0.26 for CHD, h2 = 0.22 for CED and h2 = 0.40 for OCD. The additive genetic correlation between CHD and CED was 0.31, between CHD and OCD 0.25, and between CED und OCD -0.49. A further multivariate analysis of the prevalence of the FCP (fragmented coronoid processus), CHD and OCD revealed a heritability of h2 = 0.59 for FCP. The additive genetic correlations among FCP and CHD as well CED except FCP were positive, but negative with OCD. Multivariately estimated breeding values will lead to higher genetic progress because the correlation structure of the traits can be taken into account and possible genetic antagonisms among traits are better reflected in the breeding values.     

Anthropometric measurements of the scapula, humerus, radius and ulna in Labrador dogs with and without elbow dysplasia

Objective To determine if anthropometric measurements of the Labrador scapula, humerus, ulna and radius, or their ratios, are related to the presence of elbow dysplasia (ED). Methods Digital calliper measurements of the lengths of the left scapula, humerus, radius and ulna, and their ratios, were analysed by gender in 103 volunteer Labradors (41 dogs, 62 bitches) against the ED radiological scores derived by the International Elbow Working Group (IEWG). The IEWG score is an umbrella score used to classify for ED and includes fragmented coronoid process, osteochondritis dessicans, incongruity and ununited anconeal process, the last of which occurs rarely in Labradors. Results Of the 103 Labradors studied, 31 were diagnosed radiographically with ED (20 bitches (32%), 11 (27%) dogs). Scapula length was significantly shorter for bitches with ED (P = 0.02), but not for dogs with ED. However, dogs showed a trend for a difference in the ulna:radius ratio (P = 0.06), which bitches did not. Although a greater percentage of bitches than dogs had ED in this study, the difference was not statistically significant. Conclusions Labrador bitches diagnosed with ED have a shorter scapula, which is a new finding associated with this condition. The difference in presentation associated with gender is unexpected and further research is recommended.     

Estimates of genetic parameters for hip and elbow dysplasia in Finnish Rottweilers

Data from 2,764 Rottweiler dogs born from 1987 to 1996 were analyzed with a Restricted Maximum Likelihood procedure using a mixed linear animal model to obtain variance component estimates for hip and elbow dysplasia. The data included 2,764 hip dysplasia and 2,278 elbow dysplasia records. Hip joints were scored as normal (0), borderline (1), slight (2), moderate (3), and severe (4, 4.5, and 5) hip dysplasia. Elbow joints were graded normal or borderline (0), slight (1), moderate (2), and severe (3) elbow dysplasia. The mean for the hip scores was 1.07 and for the elbow scores .60. Environmental effects influencing hip dysplasia were age, birth year, birth year x season interaction, and experience of the veterinarian responsible for x-raying the dog. For elbow dysplasia, statistically significant effects were age, birth year, sex of the dog, and panelist responsible for each screening. Estimates of heritability for hip and elbow dysplasia were .58 +/- .04 and .31 +/- .04, respectively, with a genetic correlation of .37 +/- .08 between the traits. Genetic improvement of almost one genetic standard deviation was observed in both traits during the 10 yr covered by the data.     

Estimated genetic parameters for growth traits of German shepherd dog and Labrador retriever dog guides.

A desirable dog guide weighs 18 to 32 kg and measures 53 to 64 cm in height at the withers as an adult. Heritabilities and genetic correlations were estimated for birth weight, 42-d weight, mature weight, and mature height for 2,334 German shepherd dogs and 2,028 Labrador retrievers raised by the Seeing Eye, Inc., Morristown, NJ, from 1979 to 1997. Data included 5,006 observations for German shepherd dogs from 113 dams and 33 sires and 4,123 observations for Labrador retrievers from 89 dams and 29 sires. A mixed effects model was considered with sex and birth year as fixed effects. Random effects were animal, maternal, and litter incorporating all pedigree information available. A derivative-free REML method was used to estimate parameters. The maternal component was higher than the additive genetic component for birth weight. Heritability of mature weight was estimated as 0.57 +/- 0.07 for German shepherd dogs and 0.44 +/- 0.07 for Labrador retrievers. Mature height heritability was estimated as 0.35 +/- 0.08 for German shepherd dogs and 0.46 +/- 0.08 for Labrador retrievers. Selection for lighter dogs at maturity is predicted to decrease the average mature height, and selection for taller dogs at maturity is predicted to increase the average mature weight. The estimated genetic parameters will aid in the development of strategies to increase the probability of breeding dogs for optimum mature size.     

Canine elbow dysplasia and primary lesions in German shepherd dogs in France

Five hundred and twenty German shepherd dogs were screened for elbow dysplasia. The following primary lesions were analysed: joint incongruity (JI), fragmented medial coronoid process (FCP), osteochondrosis or osteochondritis of the medial humeral condyle and ununited anconeal process (UAP). Three radiographic views were used for each joint to achieve a definitive diagnosis. The prevalence of elbow dysplasia was 19.4 per cent. The most frequent lesion was JI (16.3 per cent), followed by FCP (11.3 per cent). UAP was diagnosed rarely (1.1 per cent). Combinations of lesions were very frequent (42.2 per cent of the dysplastic elbows). Although these results may be biased due to prescreening of dogs with UAP, it should be highlighted that JI and FCP occur frequently in German shepherd dogs and are probably the most common primary lesions of elbow dysplasia, although they have been under-reported until now.     

The significance of elbow dysplasia (ED) for breeding in Bernese Mountain Dogs in Germany

Results from the elbow dysplasia screening program in Bernese Mountain Dogs of Germany were analysed in respect to its relevance for genetic evaluation and breeding. In total 2677 gradings were used. The grading was performed radiographically according to the recommendations of the International Elbow Working Group (IEWG). 75.8% of the dogs were free from visible dysplastic signs, 10.8%, 6.8% and 5.5% were classified to be of Grade 1, 2 and 3, respectively. 1.1% were classified as a borderline case between ED-free and Grade 1. A slight reduction of ED could be observed over years. Males had a 3.1 higher rate of dysplasia than females. Treating ED as a numerical trait, coded proportional to the severity of clinical relevant signs, gave a heritability estimation of 0.188 and a maternal effect of 0.07. From different mating combinations it was found, that ED average was higher in the progeny if one mate was affected but there was no increase in the prevalence with increasing grade of ED in the affected mates. About 10% more affected dogs could be observed, if one mate is affected. Heritability for dichotomic coding the trait was found to be 0.20. From these results can be suggested, that the differentiation in various grades of ED to describe the clinical relevance for the specific dog is helpfull, however, from a breeders point of view, dogs with ED should be treated equally for genetic evaluation.     

Genetic analysis of presumed inherited eye diseases in Tibetan Terriers

We analysed the systematic environmental influences and the additive genetic variation for the presumed inherited eye diseases (PIED), membrana pupillaris persistens, distichiasis, primary lens luxation, non-congenital cataract, and progressive retinal atrophy, in Tibetan Terriers. Data were obtained from the International Kennel Club for Tibetan dog breeds in Germany. PIED were recorded in the years 1987 to 2001 by standardised protocols of the Dortmunder Kreis, the association for diagnosis of inherited eye diseases in animals (DOK). The material included 849 Tibetan Terriers from 596 litters in 203 different kennels. The multivariate linear animal model using residual maximum likelihood methods regarded the fixed effects of sex, birth year, experience of the veterinary ophthalmologist, litter size, percentage of examined dogs per litter, inbreeding coefficient, and age at examination. The common environment of the litter and the additive genetic effect of the animal were taken into account as randomly distributed effects. The heritability estimates for PIED in Tibetan Terriers were h2=0.17+/-0.04 (membrana pupillaris persistens), h2=0.04+/-0.03 (distichiasis), h2=0.13+/-0.04 (primary lens luxation), h2=0.13+/-0.04 (non-congenital cataract), and h2=0.49+/-0.08 (progressive retinal atrophy). The additive genetic correlation between non-congenital cataract and progressive retinal atrophy was highly positive rg=0.76+/-0.11, while that between membrana pupillaris persistens and progressive retinal atrophy rg=-0.43+/-0.14 was highly negative. The number of examinations performed by the veterinary ophthalmologists was associated with higher heritabilities for non-congenital cataract and progressive retinal atrophy. We concluded from our analysis that all investigated PIED in Tibetan Terriers are genetically influenced.     

Sensitivity and specificity of radiography for detection of elbow incongruity in clinical patients

Elbow incongruity is an important factor regarding the treatment and prognosis of elbow dysplasia. Our purpose was to determine the sensitivity and specificity for radiographic detection of elbow incongruity in clinical patients, to establish inter- and intraobserver variation for different parameters, and to evaluate the possibility of radiographic grading of incongruity. Standard radiographic projections were acquired from 29 incongruent and nine congruent elbows of dogs of various ages and breeds. Computed tomography (CT) was used to diagnose and grade the incongruity. All radiographs were evaluated by four observers for detection and grading of elbow incongruity. Sensitivity, specificity, inter- and intraobserver variability were calculated. The mean sensitivity for detection of incongruity was very good (88.8%) with a mean specificity of 91.7%. Correct grading of incongruity was difficult. The radioulnar step and the widening of the humeroulnar and humeroradial joint space were seen most frequently. Intraobserver and interobserver variability were fair to excellent (Kappa = 0.372-0.809), depending on the investigated parameters. Radiography is valuable to screen for elbow incongruity. In over 91% of the patients, a clear distinction could be made between a congruent and an incongruent joint grading was not possible.     

In vitro validation of a technique for assessment of canine and feline elbow joint collateral ligament integrity and description of a new method for collateral ligament prosthetic replacement

Objective— To assess the ability of an operator to differentiate intact from transected canine and feline elbow joint collateral ligaments (CL) using a reported manipulative test (Campbell's test) and to determine the potential for elbow joint luxation in canine and feline elbows with intact, transected, and surgically stabilized CL. Study Design— In vitro biomechanical study. Sample Population— Canine (n=6) and feline cadavers (n=3). Methods— Thoracic limb specimens were mounted on a custom‐built jig with the elbows and carpi fixed in 90° of flexion. Angles of pronation and supination were recorded after applying rotational forces to the manus. Attempts were made to manually luxate each elbow with intact CL. Constructs were re‐evaluated after sequential sectioning of the medial (MCL) and lateral (LCL) collateral ligaments and after insertion of a new CL prosthesis. Results— Mean (±SD) angles of rotation in dogs increased from 27.3±8° (range, 16.7–41.3°) in pronation to 58.9±9.2° (range, 38–88.3°) after sectioning the MCL and from 45.5±10.8° (range, 30.7–67.3°) in supination to 68.9±17.2° (range, 45–94°) after sectioning the LCL. Angles of pronation and supination were subject to significant interanimal variability, with a strong correlation between increasing animal weight and smaller angles of rotation. Elbow luxation in dogs was not possible unless at least the LCL was transected. In cats, mean angles of rotation increased from 49.8±14.9° (range, 30.7–70°) in pronation to 99.1±17.6° (range, 79–111.7°) after sectioning the MCL and from 128.7±18.8° (range, 108.3–151.7°) in supination to 166.7±13.1° (range, 157.3–181.7°) after sectioning the LCL. Luxation in cats was not possible unless both CL were cut. Use of the ligament prosthesis without primary CL repair reliably prevented reluxation in all canine and feline elbows. Conclusions— Campbell's test allowed reliable differentiation of intact, transected and surgically stabilized canine and feline elbow joint CL in a cadaveric model. Luxation could not be performed by application of rotational forces to specimens with intact CL. Clinical Relevance— Clinical examination findings, specifically Campbell's test, can be used to determine elbow CL integrity in dogs and cats. The contralateral elbow should be used as a control, because of interanimal variability in angles of rotation.     

Estimation of genetic parameters for radiographic signs of hip dysplasia in Labrador Retrievers

The aim of this study was the analysis of environmental factors and estimation of genetic parameters for hip dysplasia in Labrador Retrievers. We analysed hip dysplasia scores of 2970 dogs from the official screening programme of the Labrador Club Deutschland (LCD) according to the FCI protocols. Traits evaluated were HD-Mit (average value of HD scores), HD-Max (higher score of both hip joints), HD-LI and HD-RE (HD score of the left or right hip joint). A linear animal model was employed to estimate heritabilities, additive genetic and residual correlations using Residual Maximum Likelihood (REML). Only inbreeding was significant after testing all non-genetic effects. Higher inbreeding coefficients were associated with higher HD scores. Heritability estimates and their standard errors were 0.38 +/- 0.04 for HD-Mit, 0.40 +/- 0.04 for HD-Max, 0.33 +/- 0.03 for HD-LI and 0.38 +/- 0.04 for HD-RE. The additive genetic correlation between HD-LI and HD-RE was 1. Heritability for female dogs was 0.31 and 0.30 for male dogs. The analysis of HD scores of Labrador Retrievers showed that the highest HD score of the hips should be used in breeding programmes, that heritabilities are not different among females and males, and that genetic components are much more important than environmental factors.     

Comparison of two classification protocols in the evaluation of elbow dysplasia in the dog

The incidence of elbow disease based solely on arthrosis (ARTH) score was compared with a protocol using a combination of ARTH score plus a score for primary lesions (ED score). The population of dogs studied included 425 Bernese mountain dogs and 22 dogs of other breeds. The overall agreement between the two systems was high. However, 12 per cent of ARTH-score negative cases were positive using the ED score. This difference was statistically significant (P<0·005). The female:male ratio of the dogs missed using the ARTH score was 2:1. The proportion of dogs affected with arthrosis increased with age, male dogs being affected more frequently. The development of arthrosis depends not only on age and breed, but probably also on gender. Thus, screening for elbow dysplasia should be based on at least two radiographic projections, including arthrosis and primary lesions. As the vast majority of dogs in this study were Bernese mountain dogs, conclusions are valid only for this breed.     

Measurement of angles of abduction for diagnosis of shoulder instability in dogs using goniometry and digital image analysis

OBJECTIVE: To compare abduction angles of shoulders with medial instability and unaffected shoulders in the same dogs and in age- and breed-matched dogs. STUDY DESIGN: Case-control study. ANIMALS: Dogs with medial instability of the shoulder (n=33) and 26 control dogs. METHODS: Dogs were sedated and positioned in lateral recumbency with both scapulas parallel to the table. With the elbow and shoulder in extension, the non-recumbent limb was maximally abducted and the angle between the scapular spine and lateral aspect of the brachium measured with a goniometer; a digital image was taken from the cranial aspect. Both techniques were performed in triplicate by 2 examiners. Mean abduction angles for each shoulder were determined from goniometric measurements and image analysis. Data were analyzed for significant differences between affected and unaffected shoulders, measurement techniques, and examiners. Strength of correlation between measurement techniques was determined. RESULTS: Mean abduction angles for shoulders with instability (53.7+/-4.7 degrees goniometric, 51.2+/-4.9 degrees image) were significantly (P<.001) larger than for all unaffected shoulders (32.6+/-2.0 degrees goniometric, 30.9+/-2.3 degrees image). In dogs diagnosed with instability, affected shoulders had significantly (P<.001) larger abduction angles than the contralateral (unaffected) shoulders. No significant differences were identified between right and left shoulders for control dogs, measurement techniques, or examiners. A strong (r=0.90) significant (P<.001) positive correlation between measurement techniques was noted. CONCLUSIONS: Shoulder abduction angles measured under sedation provide objective data for diagnosis of shoulder instability in dogs. Shoulders with clinical and arthroscopic evidence of medial instability have significantly higher abduction angles than shoulders that are considered normal. CLINICAL RELEVANCE: Determination of shoulder abduction angles should be included in the diagnostic protocol for forelimb lameness assessment in dogs.     

Review on canine elbow dysplasia: pathogenesis, diagnosis, prevalence and genetic aspects

Elbow dysplasia (ED) is a progressive skeletal disease, which may comprise osteoarthrotic changes, incongruity of the joint, a fragmented medial coronoid process (FCP), osteochondrosis dissecans of the trochlea humeri (OCD), and an ununited anconeal process (UAP). Disturbances of enchondral ossification, as well as asynchronous growth of the antebrachial bones and an increased growth rate may provoke abnormal stresses on specific locations such as the medial coronoid process, the anconeal process of the ulna or the humeral trochlea, which may result in ED. Overnutrition with calcium, vitamin D and energy had important influence on rapidity of growth and proneness to ED. ED manifests most often in young dogs less than 1 1/2 year, causing clinical signs such as (intermittent) lameness, pain on movement and altered posture of the affected limb, and radiographically secondary osteoarthrotic changes such as osteophytes or the aforementioned primary lesions. As radiographic projection of the primary lesions FCP and OCD may be difficult in the commonly used mediolateral flexed and craniocaudal views, additional projections such as mediolateral extended or anteroposterior oblique views and alternative diagnostic means such as computed tomography (CT) may be worth considering. Cases of ED are reported in various breeds, though some breeds are especially predisposed and seem to be prone to specific primary lesions. For the German shepherd dog, a breed-predisposition for UAP may be explained by broad chondral junction in association with an accelerated pattern of skeletal maturation. Heritabilities were estimated in a variety of studies, depending strongly on the type of model used. The mode of inheritance is not yet ascertained, but recently the common assumption of a polygenic mode of inheritance for ED is doubted. Instead, genetic independence was supposed between different primary lesions, and also for ED as well as for FCP major gene influence was discussed. So long, phenotypic mass selection was accomplished in different countries most often resulting in a reduced prevalence of ED. The use of best linear unbiased prediction (BLUP) methods including information on relatives and separate evaluation of genetically independent primary lesions may further improve selection against ED.     

Traumatic elbow luxation in 14 dogs and 11 cats

Objective To report the presentation and treatment of traumatic elbow luxation and to evaluate success following closed or open reduction. Design Retrospective case series conducted between April 1999 and April 2009. Methods Records of 14 dogs and 11 cats were reviewed for signalment, history, radiographic findings and treatment; 14 owners were contacted via phone questionnaire to assess for limb function following treatment. Fisher's two‐tailed P test was used to evaluate potential risk factors for lameness. Results The majority of luxations were caused by car accident and 96% of the cases luxated in a lateral direction. Closed reduction was successful in all cats and 11 dogs; 3 dogs required open reduction. Owners rated the animals' limb function as excellent (71%), good (7%), fair (22%) or poor (0%). All cats were rated excellent. An excellent result following closed reduction was achieved in 67% of canine cases. All cases of open reduction achieved fair results. All owners were satisfied with the outcome. No risk factors were significantly associated with post‐reduction lameness. Conclusions Elbow joints with good stability following closed reduction have a favourable outcome. Poor stability following closed reduction is an indication for surgery. Results suggest that cats tolerate elbow luxation better than dogs.     

Prognostic factors in treating antebrachial growth deformities with a lengthening procedure using a circular external skeletal fixation system in dogs

OBJECTIVE: To evaluate treatment of antebrachial growth deformities (AGD) with a lengthening procedure using a circular external skeletal fixation (CESF) system and to determine prognostic factors. STUDY DESIGN: Prospective clinical study. ANIMALS: Thirty-four dogs with unilateral AGD. METHODS: Length deficits, angular and rotational deformities, elbow incongruity (EI), osteoarthritis (OA) of the elbow and carpal joint, function, and cosmesis were determined before and after a CESF lengthening procedure. RESULTS: On admission, EI (21 dogs; 62%), OA of the elbow joint (17 dogs; 50%), carpal OA (12 dogs; 35%), and concomitant elbow and carpal OA (5 dogs; 7%) were common findings. Treatment significantly improved function (normal, 20 dogs; 60%) and cosmesis (normal, 22 dogs; 65%). Angular and rotational deformities were almost completely corrected with small remaining length deficits. Elbow and carpal OA increased significantly during the follow-up period. Significant correlations were demonstrated between initial elbow OA and final function (R=0.42, P=.02), initial function and final function (R=0.41, P=.02), and initial ulnar and radial deficit and final cosmesis (R=0.58, P=.0001 and R=0.45, P=.008). CONCLUSIONS: Treatment of AGD by a CESF lengthening procedure was successful despite small remaining length deficits. Initial elbow OA, function, and ulnar and radial length deficits are prognostic factors in the treatment of AGD. CLINICAL RELEVANCE: Initial elbow OA and initial function are prognostic factors in predicting the functional outcome of treatment of AGD with a CESF lengthening procedure in the dog.     

Genetic analysis of the prevalence of abomasal displacement and its relationship to milk output characteristics in German Holstein cows

Genetic parameters for the prevalence of abomasal displacement and for milk yield traits were estimated using a data set of 3578 cows. The animals originated from 50 farms near Hanover being under the official milk recording scheme. At these farms all cases of abomasal displacement in German Holsteins were registered from July 2001 to January 2003. Using REML heritability estimates in linear animal models were h2 = 0.034 +/- 0.014, h2 = 0.017 +/- 0.013 and h2 = 0.029 +/- 0.011 for all cases of abomasal displacement, leftsided abomasal displacement and rightsided abomasal displacement, respectively. Additive genetic correlations between all cases of abomasal displacement and milk yield traits were small, ranging from rg = -0.20 (fat content) to rg = 0.08 (milk kg). However, there was a highly positive additive genetic correlation between leftsided abomasal displacement and milk yield of rg = 0.683 +/- 0.227. Leftsided abomasal displacement was correlated additive genetically to fat and protein yield, fat and protein content with rg = 0.595 +/- 0.297, r9 = 0.653 +/- 0.250, rg = -0.768 +/- 0.3280 und rg = -0.643 +/- 0.354, respectively. The additive genetic correlation to the ratio between fat and protein content was rg = -0.585 +/- 0.470. For rightsided abomasal displacement, additive genetic correlations were of similar size but with reversed signs. The estimates obtained for the residual correlations were negligibly small throughout.