[Estimation of population genetic parameters and breeding values for elbow dysplasia in Rottweilers]

We analysed scores of elbow dysplasia following the IEWG protocol from the official screening programme of the Allgemeiner Deutscher Rottweiler Club (ADRK). The data set included X-rays from 5100 Rottweiler dogs born between 1995 and 2004. Out of these 5,100 dogs, 46.9% were free from ED, 9.8% showed borderline signs (ED-UG), 31.8% ED-grade 1 (mild ED), 10% ED-grade 2 (moderate ED) und 1.6% ED-grade 3 (severe ED). Male dogs were more often affected by ED-grade 2 and 3 than female dogs. Traits analysed were ED-grade (dogs free from ED and dogs with ED-grades 1 to 3) and borderline ED (ED-UG). Birth year, birth season and inbreeding coefficient were significant for ED-grade. Higher inbreeding coefficients were associated with higher ED scores. ED-UG was significantly influenced by birth year and the interaction of birth year and birth season. A bivariate linear animal model was employed to estimate heritabilities using Residual Maximum Likelihood (REML) for ED-grade and ED-UG. Heritability estimates and their standard errors were 0.387 +/- 0.028 for ED-grade and 0.017 +/- 0.009 for ED-UG. The additive genetic correlation between ED-grade and ED-UG was -0.5. Heritabilities for ED-grade in female and male dogs were 0.350 +/- 0.033 and 0.497 +/- 0.047. We do not recommend use of ED-UG in breeding work because of the low heritability estimate and the negative additive genetic correlation with ED-grade.

[Population genetic analysis of behaviour traits in Hovawart dogs]

The aim of this study was to determine genetic and environmental influences on behaviour traits in Hovawart dogs. Trait definition was based on a survey which was conducted by the breeding association for Hovawart dogs in Germany in 2002. Questionnaires of 601 dogs born between 1991 and 2001 were used for the analysis of 23 traits that were grouped to the following five trait complexes: behaviour towards strangers and kids, response to external influences, response to dominance gestures of the owner, response to other dogs, and behaviour towards other dogs. Analyses were performed using residual maximum likelihood in multivariate linear animal models. Heritability estimates ranged between h2 = 0.01 and h2 = 0.22 (standard error < or = 0.07). Within the trait complexes, additive genetic correlations were in most cases moderately to highly positive (rg = 0.20 to rg = 1.00); in few cases they were clearly negative (up to rg = -0.81). Residual correlations were in the range of re = -0.12 to re = 0.50. In summary, the results of this study support the heritable nature of behaviour traits in the Hovawart dogs. Accordingly, traits like the response of the dog to unfamiliar situations (h2 = 0.20) and the behaviour towards strangers approaching the home property (h2 = 0.22) may be considered when selecting breeding animals.

[A rare occurrence of dicephalus, scoliosis and complex heart anomalies in a male black and white German Holstein calf]

In a dairy farm in Lower Saxony, a male black and white German Holstein calf showed two partially fused heads, scoliosis of the thoracal vertebral column and a high-graded dyspnoea. The animal was sired by a bull used in artificial insemination. Further affected calves were not known at this farm. The radiographic examination of the animal verified the diagnosis of a dicephalus. The pathological-anatomical examination revealed a complex malformation of the heart similar to the human Eisenmenger-complex. Several environmental causes like intoxication, rectal palpation for gestation diagnosis, infections by bovine virus diarrhoea or infectious bovine rhinotracheitis viruses could be ruled out by anamnesis and virological examinations. Thus, we supposed a hereditary background for this defect.

INHBA-associated markers as candidates for stallion fertility

The inhibin beta A (INHBA) gene was chosen as candidate for stallion fertility and analysed for intragenic markers to find associations with pregnancy rate per oestrus. Intragenic single nucleotide polymorphisms (SNPs) were developed in order to perform an association and haplotype analysis using the least square means (LSM) of the pregnancy rate per oestrus for stallions as well as breeding values (BVs) for the embryonic and paternal component of the pregnancy rate per oestrus. The polymorphisms were genotyped in 161 Hanoverian warmblood stallions. Insemination records from approximately 20,000 Hanoverian warmblood mares were used to calculate LSM for stallions and to predict the paternal and embryonic component of BVs for the pregnancy rate per oestrus. We demonstrated significant associations of single markers and haplotypes with the LSM and the embryonic and paternal component of BVs for the pregnancy rate per oestrus. This is the first report on INHBA as an associated candidate gene with the LSM of stallions and the paternal and embryonic component of BVs for the pregnancy rate per oestrus.

Mapping quantitative trait Loci for left-sided displacement of the abomasum in German Holstein dairy cows

A whole-genome scan using an affected paternal half-sib design was utilized to detect quantitative trait loci (QTL) for left-sided displaced abomasum (LDA) in German Holsteins. A total of 360 animals from 14 paternal half-sib families were genotyped, for a total of 306 polymorphic microsatellites. For a whole-genome scan, 221 markers were equally distributed over all 29 bovine autosomes, with an average distance of 13.7 cM. For fine-mapping, a total of 85 additional microsatellites were used. We identified genome-wide significant QTL on Bos taurus autosome (BTA) 1 (54.6 to 58.3 cM) and on BTA3 (5.9 cM). Furthermore, 3 chromosome-wide significant QTL were located on bovine chromosomes 21, 23, and 24. In addition, we found 11 QTL that cosegregated in grandsire families but that were not significant in the across-family analysis. These QTL were located on BTA5, 6, 10, 12, 15, 16, 17, 19, 23, and 26. This study is the first report on QTL for LDA and is a first step toward identifying single nucleotide polymorphisms for LDA-QTL.

Evaluation of the titin-cap gene (TCAP) as candidate for dilated cardiomyopathy in Irish wolfhounds

Dilated cardiomyopathy (DCM) is a myocardial disorder characterized by left ventricular dilatation and impaired systolic contraction. Irish wolfhounds (IW) and other large breed dogs are most commonly disposed to DCM. We analyzed the titin-cap (TCAP, telethonin) gene as candidate for DCM. Genomic DNA was analyzed in eight DCM affected and five DCM-free IWs. cDNA was sequenced in one DCM-affected IW and two unaffected dogs, one Tibetan terrier and one Dachshund. Compared to the Boxer reference sequence, one sequence difference was identified in the 3'UTR and two in the intron sequence. In the IWs the sequences were monomorphic. In order to rule out a breed-specific haplotype that predisposes to DCM, the polymorphisms were genotyped in 24 Elo dogs, a breed mix established from nine different breeds. The analysis showed that the mutations were not restricted to IW. Moreover, 80% of the Elos were homozygous for the IW haplotype. We conclude that TCAP can most likely be eliminated as cause for DCM in IWs.

Effect of polymorphisms in four candidate genes for fertility on litter size in a German pig line

We carried out an SNP discovery project in pigs for candidate genes playing potentially important roles in embryonic development. Using eight pigs one each from eight breeds (Meishan, Mangalitza, Duroc, Pietrain, German Landrace, Hampshire, Husum Red Pied, German Large White), 36 SNPs were identified in intronic sequences of 21 porcine candidate genes based on sequencing of PCR products. The primer pairs were designed using porcine EST sequences allowing amplification of introns. These SNPs were tested for their association with the number of piglets born alive in German Large White sows using a discordant approach. Significant effects (p < 0.001 and p < 0.05, respectively) of intronic SNPs on litter size were found for four genes: mitogen-activated protein kinase kinase kinase 3 (MAP3K3), vascular endothelial growth factor receptor (KDR), erbb2 interacting protein (ERBB2IP) and peroxisome proliferator-activated receptor delta (PPARD). These SNPs can be further tested in upcoming association studies for their influence on litter size in different breeds using larger sample sizes.

A 4,103 marker integrated physical and comparative map of the horse genome

A comprehensive second-generation whole genome radiation hybrid (RH II), cytogenetic and comparative map of the horse genome (2n = 64) has been developed using the 5000rad horse x hamster radiation hybrid panel and fluorescence in situ hybridization (FISH). The map contains 4,103 markers (3,816 RH; 1,144 FISH) assigned to all 31 pairs of autosomes and the X chromosome. The RH maps of individual chromosomes are anchored and oriented using 857 cytogenetic markers. The overall resolution of the map is one marker per 775 kilobase pairs (kb), which represents a more than five-fold improvement over the first-generation map. The RH II incorporates 920 markers shared jointly with the two recently reported meiotic maps. Consequently the two maps were aligned with the RH II maps of individual autosomes and the X chromosome. Additionally, a comparative map of the horse genome was generated by connecting 1,904 loci on the horse map with genome sequences available for eight diverse vertebrates to highlight regions of evolutionarily conserved syntenies, linkages, and chromosomal breakpoints. The integrated map thus obtained presents the most comprehensive information on the physical and comparative organization of the equine genome and will assist future assemblies of whole genome BAC fingerprint maps and the genome sequence. It will also serve as a tool to identify genes governing health, disease and performance traits in horses and assist us in understanding the evolution of the equine genome in relation to other species.

Evaluation of bone strength, keel bone deformity and egg quality of laying hens housed in small group housing systems and furnished cages in comparison to an aviary housing system

Abstract. The objective of the study was to assess bone breaking strength, keel bone status and egg quality parameters of Lohmann Silver (LS) and Lohmann Tradition (LT) layers housed in small group systems (SG) and furnished cages (FC) in comparison to an aviary system. At the end of the 3rd, 6th, 9th and 11th laying month, approximately 40 hens were randomly chosen from each housing system and slaughtered (478 hens in total). Humerus and tibia strengths were analysed using a three-point-bending machine. Keel bone status was evaluated on a scale from 1 (severe) to 4 (no deformity). Shell breaking strength was measured every four weeks, totalling 4,887 eggs. Statistical analyses were performed using the MIXED procedure of SAS. Humerus and tibia strengths of LS layers housed in SG were significantly higher compared to LS hens kept in FC. Bone breaking strengths of humerus and tibia in LS and LT layers were highest in the aviary system and the differences to the other housing systems were significant. No significant differences in tibia and humerus bone breaking strengths were found between SG and FC for LT hens. Keel bone status was not significantly influenced by housing system or laying strain. For both hybrids, shell breaking strength was significantly lower in SG compared to FC and aviary system. The results showed that SG systems can significantly enhance bone breaking strength for LS layers in comparison to hens kept in FC. The lower shell breaking strength of eggs in SG might slightly impair economic aspects.

Genes on bovine chromosome 18 associated with bilateral convergent strabismus with exophthalmos in German Brown cattle

PURPOSE

Bilateral convergent strabismus with exophthalmos (BCSE) is a widespread inherited eye defect in several cattle populations. Its progressive condition often leads to blindness in affected cattle and shortens their length of productive life. Furthermore, breeding with BCSE-affected animals is forbidden by the German animal welfare laws. We performed a mutation and association analysis for three candidate genes (troponin T type 1 [TNNT1], retinol dehydrogenase 13 [RDH13], and TCF3 fusion partner [TFPT]), which are located within the previously identified BCSE-linked region on the telomeric end of bovine chromosome 18 (BTA18). In addition, we developed single nucleotide polymorphisms (SNPs) within these three candidate genes and nine other genes that are contained in this genomic BCSE-region to perform association analyses with BCSE in German Brown cattle.

METHODS

We performed cDNA analyses of all three candidate genes using eye tissues of three affected German Brown cows and three unaffected controls. Furthermore, we screened the exonic and the adjacent genomic sequences of RDH13, TNNT1, and TFPT using four BCSE-affected and four controls of German Brown cattle. Here, we included all exons of RDH13 and those exons of TNNT1 and TFPT for which SNPs were detected by cDNA analyses. In addition, we developed 21 polymerase chain reaction (PCR) products for 17 more genes in the BCSE region and searched them for polymorphisms. All markers detected were genotyped in 48 BCSE-affected German Brown cows and 48 breed and sex matched controls and tested for association with BCSE.

RESULTS

In total, we detected 29 SNPs in 12 genes. In the coding sequence of the three candidate genes, we identified 10 exonic SNPs and a new splice variant of TNNT1. Four SNPs were associated with the BCSE phenotype in single marker-trait analyses. These SNPs were located within DHDH (dihydrodiol dehydrogenase dimeric), CPT1C (carnitine palmitoyltransferase 1C), TNNT1, and NALP7. The marker-trait association for haplotypes including five SNPs of CPT1C, SYT5 (synaptotagmin V), RDH13, and NALP7 (NLR family, pyrin domain containing 7) revealed a significant association with BCSE. We identified three individual haplotypes that were significantly associated with BCSE. These haplotypes spanned the region from 56.05 Mb to 62.87 Mb on BTA18.

CONCLUSIONS

The haplotype association analysis corroborated the results of the linkage study that the telomeric end of BTA18 harbors a gene responsible for BCSE and further refines the BCSE region to a 6.82 Mb interval ranging from 56.05 Mb to 62.87 Mb on BTA18.

[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.

[Familial canine pituitary-dependent hyperadrenocorticism in wirehaired Dachshunds]

Canine pituitary hyperadrenocorticism (Cushing's disease) caused by neoplasia of the corticotrope cells is one of the most common endocrine diseases especially in smaller dog breeds. Cushing's disease was diagnosed in eleven wire-haired Dachshunds and for further six wire-haired Dachshunds Cushing's disease was suspected on the basis of clinical signs. A joined pedigree could be ascertained for all these 17 dogs. Eleven of these dogs were so closely related to each other, that they were summarized in four nucleus families. Two fullsiblings were examined by means of clinical, laboratory diagnostic and morphological methods. The main lesions consisted of atrophic dermatosis with alopecia, increase of activity of liver enzymes in plasma and bilateral adrenocortical hyperplasia and therefore corresponded to the typical signs of a secondary hyperadrenocorticism. A rather unusual finding was the pituitary carcinoma in one of these dogs. Similarly to human patients affected by hyperadrenocorticism, real-time PCR analysis showed a 2.9-fold increase of expression of the canine MDR1 gene in the liver of one affected wirehaired Dachshund. This study documents the first familial occurrence of pituitary-dependent hyperadrenocorticism in wirehaired Dachshunds, the overexpression of the MDR1 gene in the dog and the third case of familial hyperadrenocorticism in dogs ever described.

Molecular characterization and SNP development for the porcine IL6 and IL10 genes

Different cytokines are secreted in response to specific microbial molecules referred to as pathogen associated molecular patterns (PAMPs). Interleukin 6 (IL6) and interleukin 10 (IL10), both secreted by macrophages and lymphocytes, play a central role in the immunological response. In this work we obtained the genomic structure and complete DNA sequence of the porcine IL6 and IL10 genes and identified polymorphisms in the genomic sequences of these genes on a panel of ten different pig breeds. Comparative intra- and interbreed sequence analysis revealed a total of eight polymorphisms in the porcine IL6 gene and 21 in the porcine IL10 gene, which include single nucleotide polymorphisms (SNPs) and insertion deletion polymorphisms (indels). Additionally, the chromosomal localization of the IL10 gene was determined by FISH and RH mapping.

Linkage of bilateral convergent strabismus with exophthalmus (BCSE) to BTA5 and BTA18 in German Brown cattle

Bilateral convergent strabismus with exophthalmus (BCSE) is a widespread inherited eye defect in several cattle populations. Its progressive condition often leads to blindness in affected cattle and decreases their usability. Furthermore, the German animal welfare laws prevent breeding with animals whose progeny are expected to be affected by genetic defects. Identifying genes involved in the heredity of BCSE should lead to insights into the molecular pathogenesis of this eye disease and permit the establishment of a genetic test for this disease. A whole-genome scan for 10 families containing a total of 159 genotyped individuals identified two BCSE loci. One BCSE locus mapped to the centromeric region on bovine chromosome (BTA) 5 and the other BCSE locus mapped to the telomeric region of BTA18. Thus, it is possible that two genes are involved in the development of BCSE. Alternatively, one of these loci could be the cause for the development of BCSE and the other locus could affect the progression and severity of the defect.

Analysis of systematic and genetic effects on the prevalence of different types of primary lens opacifications in the wild-boar-colored wirehaired Dachshund

The aims of this study were to analyze the influence of systematic environmental effects on the prevalence of primary non-congenital cataract (CAT), fibreglass cataract in the nucleus (FCN), and prominent suture lines (PSL) and to estimate the heritabilities of these eye diseases in the wild-boar-colored wirehaired Dachshunds (WWD) bred in the German Dachshund Club 1888 e.V. (DTK). Data included 2,430 WWD born between 1995 and 2003 that were examined between 1996 and 2005 by veterinary ophthalmologists. CAT was diagnosed in 3.83% of the 2,430 dogs, FCN in 3.74%, and PSL in 2.76%. Sex, size, inbreeding coefficient, the age of the dog at examination, experience of the veterinary ophthalmologist and the additive genetic effect of the animal were considered in the multivariate linear model. The age of the dog at examination had a significant influence on the prevalence of FCN. The degree of experience of the veterinary ophthalmologist significantly influenced the prevalence of FCN and PSL. Using a transformation into the Dempster-Lerner threshold model, heritability estimates (h(DL)2) for WWD were h(DL)2 = 0.39 +/- 0.13 for CAT, h(DL)2 = 0.36 +/- 0.11 for FCN and h(DL)2 = 0.49 +/- 0.12 for PSL. Positive genetic correlations (r(g)) were found between CAT and FCN (r(g) = 0.58 +/- 0.21), between PSL and FCN (r(g) = 0.83 +/- 0.23), and between CAT and PSL (r(g) = 0.79 +/- 0.06). The eye diseases investigated here in the Dachshund were found to be genetically influenced and positively correlated traits.

[Review of literature and results from test matings of East Friesian milk sheep affected with brachygnathia inferior]

Shortness of the lower jaw (brachygnathia inferior, underbite, overshot, parrot mouth) is an inborn and mostly hereditary malformation often seen in many sheep breeds. Chromosomal anomalies are generally not involved in brachygnathia inferior. Viral infections, teratogenic drugs and alkaloids of plants often lead to craniofacial malformations associated with brachygnathia inferior. A maternal deficiency of iron is discussed as a cause for brachygnathia inferior. We performed a three-year breeding trial using mainly East Friesian milk sheep affected by brachygnathic occlusion. Mating schemes included affected by affected and affected by unaffected matings. In the breeding trial, 60 lambs were born and from these 37 animals had variable degrees of brachygnathia inferior. The brachygnathic condition increased with rising age of the lambs. Extremely affected lambs showed palatine ulcers and growth retardation. Moreover, some animals had abnormal positions of the incisor teeth, distortion of the lower jaw and deformities of the external ear. Analysis of the pedigree did not support a monogenic inheritance pattern. An oligogenic inheritance including a dominant and recessive locus responsible for the major gene effects and possibly further modifying loci appeared much more likely. Other causes for brachygnathia inferior such as viral infections and anemia of the ewes could be ruled out. Chromosomal abnormalities were not evident and thus, large chromosomal defects were not associated with brachygnathia inferior.

Effect of polymorphisms in the genes for LIF and RBP4 on litter size in two German pig lines

The association of two diallelic polymorphisms in the porcine genes for leukaemia inhibitory factor (LIF) and retinol-binding protein 4 (RBP4) with number of piglets born alive (NBA) in two German pig lines was studied. The investigated single nucleotide polymorphism (SNP) in the porcine LIF gene has been located in the 3'-untranslated region of its third exon, whereas the SNP in the RBP4 gene genotyped in this study is intronic. At the LIF locus the allele frequencies were 0.613 for the A allele and 0.387 for the B allele in German Landrace (GL) and 0.276 for A and 0.724 for B in German Large White (GW). At the RBP4 locus, the allele frequencies were 0.586 for the A allele and 0.414 for the B allele in GL and 0.733 for A and 0.267 for B in GW. There was a significant additive effect of the LIF B allele on NBA in GW over all parities (p <or= 0.05) and a significant positive dominance effect of 0.69 +/- 0.22 (p = 0.002) was observed for first parity on NBA in GL. For RBP4, no association of genotypes and NBA was detected in GW but a significant additive effect of the A allele of 0.24 +/- 0.11 (p = 0.027) and a significant dominance effect of 0.31 +/- 0.13 (p = 0.020) were found in GL over all parities and confirmed through the evaluations by parity.

Review of prevalence, genetic aspects and adverse effects of the mdr1-1Delta mutation in dogs

A mutation in the canine MDR1 gene causes multiple drug sensitivity in dog breeds of the Collie lineage. Dogs with this genetic defect show severe neurotoxic adverse effects if they are treated with particular drugs. Clinical signs depending on the administered drug and its concentration vary from mild toxicosis with salivation and disorientation to severe effects with coma and finally death of the dog. Drugs which provoke adverse effects are structurally different. Although they are used for many different indications, all of these drugs are substrates of a transporting protein encoded by the MDR1 gene. This P-glycoprotein loses its normal protecting function at the tissue barriers in dogs with the mdrl-1Delta mutation. This article gives a short overview about the present state of analyses regarding the canine MDR1 gene. The genetic background, effects and prevalence in affected dog breeds of the mdrl-1Delta mutation are summarized. On the one hand, the overview might help practical veterinarians to understand the aetiology of drug sensitivity in dogs with the mdrl-1Delta mutation, and on the other hand, it might point out appendages for future research works about the canine MDR1 gene as well as for breeding strategies in affected dog breeds.

Association study of candidate genes for primary cataracts and fine-mapping of a candidate region on dog chromosome 1 in Entlebucher mountain dogs

PURPOSE

The Entlebucher mountain dog (EMD) shows a high incidence of primary non-congenital cataracts (CAT). Because of the late-onset of CAT, it is difficult to exclude affected animals from breeding. A screen of candidate genes should help to identify the genes associated with CAT in EMD.

METHODS

We genotyped 39 flanking microsatellite markers for 31 cataract candidate genes in 10 EMD families and tested them for linkage and association. For delimitation of a linked chromosome region on canine chromosome 1 (CFA1), we interrogated CFA1 by genotyping 30 additional microsatellites. We also sequenced the whole coding sequence with flanking intronic and untranslated regions of two candidate genes on CFA1.

RESULTS

We found a genome-wide significant genomic region on CFA1, which showed a significantly associated haplotype with the CAT phenotype in the EMDs. Sequencing two candidate genes located on CFA1 revealed three single nucleotide polymorphisms (SNPs), which were not associated with CAT.

CONCLUSIONS

We identified a putative CAT region that peaked at 96.07 Mb with genome-wide significant test statistics and extended over 1.3 Mb on CFA1 in the EMD. A significant marker-trait association based on haplotypes corroborated this CAT region. Further research is necessary to determine the gene responsible for CAT that is harbored by this linked and associated genomic region.

Haplotype analysis of the MDR1 flanking region in the dog breed Elo

A deletion mutation in the canine multidrug resistance (MDR1) gene provokes drug sensitivity in several dog breeds from the Collie lineage. A haplotype of four microsatellites containing this mdr1-1Delta mutation was conserved among affected breeds. In this study, we analysed the haplotypes of the MDR1 flanking region of 177 dogs of the breed Elo which is composed of several dog breeds including the Old English sheepdog from the Collie lineage. We detected a haplotype in the Elo breed which had previously been associated with the mutant mdr1-1Delta allele in Old English sheepdogs. Using a regression analysis for the probability of the haplotype on the proportion of genes of the founder breeds, we could exclude the Old English sheepdog as origin of this haplotype for the Elo breed. The MDR1 flanking region could be traced back to the Japanese Spitz as one of the founder dog breeds of the Elo and thus, the introgression of the mdr1-1Delta mutation into the dog breed Elo through the Collie lineage is very unlikely.

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.

Evaluation of canine heat shock transcription factor 4 (HSF4) as a candidate gene for primary cataracts in the Dachshund and the Entlebucher Mountain dog

OBJECTIVE

Testing of the cataract-causing insertion/deletion mutation in the canine HSF4 gene for its linkage and association with primary cataracts (CAT) in Dachshunds and Entlebucher Mountain dogs.

MATERIALS

Exon 9 with flanking intronic regions of the canine HSF4 gene was sequenced in 24 Dachshunds and 20 Entlebucher Mountain dogs. The HSF4 cDNA sequence of lens tissue was analyzed in a CAT-unaffected mixed-breed dog and in three CAT-affected dogs of different breeds, including a Wire-haired Dachshund, a Dachshund-mix and a German Shepherd dog.

RESULTS

In all dogs investigated here, the previously reported CAT-causing mutation did not exist. We found a single nucleotide polymorphism (SNP) in intron 9, which was neither associated nor linked with the CAT phenotype in the two dog breeds.

CONCLUSION

The CAT phenotype in the two dog breeds investigated here was not caused by the same mutation found to be associated with early-onset CAT in the Staffordshire Bull Terrier and Boston Terrier. The intronic SNP may be useful to test HSF4 for linkage with CAT in further dog breeds.

Keel bone condition in laying hens: a histological evaluation of macroscopically assessed keel bones

The objective of the present study was to conduct a corresponding histological analysis of 162 macroscopically assessed keel bones (1: severe, 2: moderate, 3: slight, 4: no deformity). Four layer lines were used and hens were kept in furnished cages, small group systems (both allowing more activities due to the provision of perches) and an aviary system, which fully conformed to the EU standards. Investigations were carried out in the 3rd, 6th, 9th and 12th laying month of two experimental trials. In 97.9% of grade 4 keel bones, no histological deviations were found, whereas in keel bones manifesting deformities of grade 1 and 2, the predominant histological observation was the incidence of fracture callus material (FCM) and new bone in the form of woven bone. FCM was also detected in 50.9% of grade 3 keel bones, whereas in 40.7%, only s-shaped deviations of keel bones were found, which were related to extended pressure loading while perching activities rather than short-duration trauma. Histological analysis showed that keel bones of grade 1 and 2 were mainly attributed to traumatic origin and therefore associated with pain experience in layers. Grade 3 keel bones manifested either FCM as a result of trauma or adaptational deformities without any evidence of a preceding fracture in response to mechanical pressure loading and were most likely not associated with pain. Therefore, histological analysis was found to be a mandatory tool when evaluating grade 3 keel bones with respect to layers'welfare. Furthermore, this analysis corroborates the findings that in aviary systems deformities of keel bones are predominantly caused by painful fractures.