From Mendel laws to whole genetic association study to decipher the swine mulefoot phenotype.

The swine mulefoot (SM) is a rare condition characterized by a non-cloven hoof due to the partial or total fusion of the phalanges. No comprehensive study has been conducted to identify associated markers with this phenotype until now. We aimed to characterize the association between SNP and the mulefoot phenotype using a Genome-Wide Association Study (GWAS). An experimental population was produced using a half-sib mating where the male had the mulefoot phenotype and the females (n = 6) had cloven hoofs. The cross resulted in 27 (47%) animals with the mulefoot characteristic and 30 (53%) normal animals, indicating the possible dominant gene action. Animals were further genotyped using the Illumina PorcineSNP50k BeadChip, and SNPs were tested for associations. Twenty-nine SNPs located on the SSC15, SSC4, and SSCX were associated with the mulefoot phenotype (p-value <5 × 10-5). Six markers were found in the intronic regions of VWC2L, CATIP, PDK3, PCYT1B, and POLA1 genes. The marker rs81277626, on SSC15:116,886,110 bp, is located in the Von Willebrand Factor C Domain (VWC2L), a possible functional candidate gene. The VWC2L is part of a biological process involved with the bone morphogenetic protein (BMP) signaling pathway, previously associated with syndactyly in other species. In conclusion, the identified markers suggest the involvement of the VWC2L gene in the SM phenotype in this population.

Genomic analysis of claw lesions in Holstein cows: Opportunities for genomic selection, quantitative trait locus detection, and gene identification.

Claw lesions are the third most important health issue in dairy cattle, after mastitis and reproductive disorders, and genomic selection is a key component for long-term improvement of claw health. The objectives of this study were to assess the feasibility of a genomic evaluation for claw health in French Holstein cows, explore possibilities to increase evaluation accuracy, and gain a better understanding of the genetic determinism of claw health traits. The data set consisted of 48,685 trimmed Holstein cows, including 9,646 that were genotyped; 478 genotyped sires were also used. Seven claw lesion traits were evaluated using BLUP, genomic BLUP, BayesC, and single-step genomic BLUP, and the accuracies obtained using these approaches were measured through a validation study. The BayesC approach was used to detect quantitative trait locus (QTL) regions associated with the 7 individual traits (digital dermatitis, heel horn erosion, interdigital hyperplasia, sole hemorrhage circumscribed, sole hemorrhage diffused, sole ulcer, and white line fissure) based on their Bayes factor. Annotated genes on these regions were reported. Genomic evaluation approaches generally did not allow for greater accuracies than BLUP, except for single-step genomic BLUP. Accuracies were moderate, but best and worst validation animals were correctly discriminated and showed significant differences in lesion frequencies. A total of 192 QTL regions were identified, including 13 with major evidence or involved for 2 of the traits. A high number of genes were present on these regions, and several had functions associated with the immune system. In particular, the EPYC gene is located close to a major evidence QTL for resistance to digital dermatitis that is also a QTL for interdigital hyperplasia (on chromosome 5, around 20.9 MB) and has been associated with Ehlers-Danlos syndrome in cattle. Genomic selection can be used to improve resistance to individual claw lesions, and several possibilities exist to improve accuracies of genomic evaluations.

Ultrasonographical examination of bovine claws through the sole horn on weight-bearing claws.

Claw horn disruptions in the bovine claw are believed to be a consequence of pressure on the sole corium from the third phalanx, which may be caused by a weakening of the suspensory apparatus in the claw. We aimed to develop an ultrasonographic method that would make it possible to measure the thickness of the soft tissue between the third phalanx and the sole horn on a weight-bearing claw. A device was developed to record the sole horn and soft tissue thickness indirectly through a polyethylene plate, and 52 feet from slaughtered cows were examined using ultrasonography, both directly and indirectly. Soft tissue and sole horn thickness measurements in the apex and the plantar part of the sole were compared with anatomical measurements of transected claws. To assess the method on weight-bearing versus non-weight-bearing claws, we examined the hind claws of 10 live cattle without transection. We found a weak correlation between the soft tissue thickness measured by ultrasound and anatomical measurements. A strong correlation was observed between the direct ultrasound approach and the developed indirect method. There was a considerable difference between weight-bearing and non-weight-bearing claws, signifying a weak or nonexistent correlation. However, this part of the study was only done on 10 live cows and the results should be interpreted with caution. We concluded that it would be possible to measure the soft tissue using an indirect ultrasound approach on a weight-bearing-claw standing on a polyethylene plate. The major difference between the results of weight-bearing versus non-weight-bearing claws suggests that future studies of the suspensory apparatus could focus on weight-bearing claws.

Testing a new surgical instrument to obtain bovine hoof biopsy samples / Teste de viabilidade de um instrumento cirúrgico para obtenção de biópsias do tecido laminar do casco de bovinos

The histological and molecular analysis of biopsy samples are fundamental steps for the understanding of physiopathology, diagnosis and prognosis of the diseases. However, harvest of tissue biopsies from hoof lamellar tissue is a procedure with limitations due to lack of effective surgical instruments and techniques. The aim of the current study is to develop and test in vivo a surgical instrument with the specific purpose of harvesting lamellar tissue in cattle. A prototype called Falcão-Faleiros' lamellotome (INPIBR102013018765-8) was designed, produced and tested. After sedation, five adult cattle were restrained in lateral recumbency and locally anesthetized in two digits. The stratum corneum was worn down using a rotary tool coupled to a 3/8" high-speed cutter until the soft tissue proximity was reached. Next, the inner edge of the worn area was bounded with a scalpel. The lamellotome was introduced to obtain and hold the sample. The histological specimens of 16mm length by 6mm depth were stained with HE, PAS, Masson's thricome and Shorr. The structures of interest were differentiated in the histological analysis without technical artifacts and a mean number of 85 epidermal laminae per sample were counted. No relevant lameness or wound complication were seen following the procedure. In conclusion the technique using the lamellotme was effective in obtaining lamellar tissue biopsy samples without causing clinical harm in cattle. The procedure showed potential to be used in clinical research or even as a supplementary diagnosis method for routine bovine podiatry.(AU)

A avaliação das propriedades histológicas e da expressão de genes e proteínas em biópsias tem sido determinante para o entendimento da fisiopatologia, o diagnóstico e o prognóstico das enfermidades. Entretanto, a obtenção de biópsias do casco é um procedimento com limitações devido à ausência de técnicas e instrumentos específicos. O objetivo foi desenvolver e testar, na espécie bovina, um instrumento cirúrgico especificamente desenvolvido para realização de biópsias de casco nominado lamelótomo de Falcão-Faleiros (INPI, BR102013018765-8). Utilizaram-se cinco bovinos adultos que foram sedados, contidos em decúbito lateral e tiveram dois dígitos anestesiados. Em seguida, uma serra circular acoplada a uma microretífica foi usada para o desgaste do estrato córneo na parede dorsal até próximo do estrato lamelar. Após incisões retilíneas delimitando a borda interna da área desgastada, utilizou-se o lamelótomo para obtenção da amostra. Os fragmentos de 16mm de comprimento e 6mm de profundidade foram fixados em formalina e processados para histologia com colorações HE, PAS, Shorr e tricrômico de Masson. Nenhum dos animais apresentou claudicação ou complicação relevantes no período pós-opertório. As amostras foram consideradas adequadas quanto à integridade das lâminas e à preservação de sua arquitetura. Obtiveram-se média de 85 lâminas epidérmicas viáveis por biópsia. Conclui-se que o lamelótomo de Falcão-Faleiros é apropriado e seguro para a obtenção de biópsias de casco em bovinos, se mostrando promissor para uso em estudos clínicos e na rotina de diagnóstico de problemas podais em bovinos.(AU)

Angular Limb Deformities: Growth Augmentation.

Angular limb deformities are seen in young foals and are defined as lateral or medial deviations of the limb in the frontal plane distal to a particular joint. Several factors can contribute to the development of an angular limb deformity. Early assessment of the level of ossification of the cuboidal bones is critical to avoid complications long term. Although most deviations self-correct with minimal intervention other than modifications in exercise and hoof trimming, some require surgical intervention in the form of growth acceleration or retardation. This article focuses on growth augmentation techniques, such as hemicircumferential transection and elevation.

A genome-wide association study identifies a region strongly associated with symmetrical onychomadesis on chromosome 12 in dogs.

Symmetrical onychomadesis causes periodic loss of claws in otherwise healthy dogs. Genome-wide association analysis in 225 Gordon Setters identified a single region associated with symmetrical onychomadesis on chromosome 12 (spanning about 3.3 mb). A meta-analysis including also English Setters indicated that this genomic region predisposes for symmetrical onychomadesis in English Setters as well. The associated region spans most of the major histocompatibility complex and nearly 1 Mb downstream. Like many other autoimmune diseases, associations of symmetrical onychomadesis with DLA class II alleles have been reported. In this study, no associated markers were revealed within any of the DLA-DRB1, -DQA1 or -DQB1 genes, and the odds for symmetrical onychomadesis in the Gordon Setters were much higher, carrying significant single nucleotide polymorphisms compared to the odds of any of the recorded DLA-DRB1/DQA1/DQB1 haplotypes. We noticed that some of the associated DLA haplotypes were different between the English Setters and the Gordon Setters. Interestingly, associated SNP chip markers showed a more consistent pattern of allelic variants related to cases or controls regardless of breed. In conclusion, the associated genetic markers identified in this study hold the potential to aid in selection of breeding animals to reduce the frequency of symmetrical onychomadesis in the dog.

[Association of skin problems with coat colour and white markings in three-year-old horses of the Franches-Montagnes breed]. / Assoziation zwischen Hautgesundheit und Fellfarbe sowie weissen Abzeichen bei dreijährigen Freibergerpferden.

In the last 30 years the amount of white markings in the population of Franches-Montagnes horses (FM) has more than doubled which has led to some controversy, particularly in respect to the health of the horses. The objective of this study was to investigate if the coat colour and white markings have an impact on selected skin diseases and hoof horn abnormalities. To this purpose 974 three-year-old FM were subjected to a clinical examination during the field and station tests organized by the FM breeding association. In 16.9% of the horses, one or several equine sarcoids were detected, 15.2% of the horses showed clinical signs of pastern dermatitis, 1.1% of insect bite hypersensitivity and 18.0% of dermatitis of other aetiology. Abnormalities of the hoof horn were found in 20.1% of the horses. The prevalence of pastern dermatitis was 2.6 times higher in legs with white markings than in legs with pigmented skin (p <0.0001). The probability ofsuffering from sunburn and hoof horn of lesser quality was increased in animals with an elevated white marking index (WAI; p = 0.022 and p = 0.038), on the other hand, horses with sarcoids had a significantly lower WAI than sound horses (p = 0.038). Our study shows that FM horses with more pronounced white markings have an increased risk to suffer from pastern dermatitis, sunburns and hoof horn abnormalities. The coat colour was not associated with skin diseases.

The feral horse foot. Part B: radiographic, gross visual and histopathological parameters of foot health in 100 Australian feral horses.

BACKGROUND: It has been proposed that the feral horse foot is a benchmark model for foot health in horses. However, the foot health of feral horses has not been formally investigated. OBJECTIVES: To investigate the foot health of Australian feral horses and determine if foot health is affected by environmental factors, such as substrate properties and distance travelled. METHODS: Twenty adult feral horses from five populations (n = 100) were investigated. Populations were selected on the basis of substrate hardness and the amount of travel typical for the population. Feet were radiographed and photographed, and digital images were surveyed by two experienced assessors blinded to each other's assessment and to the population origin. Lamellar samples from 15 feet from three populations were investigated histologically for evidence of laminitis. RESULTS: There was a total of 377 gross foot abnormalities identified in 100 left forefeet. There were no abnormalities detected in three of the feet surveyed. Each population had a comparable prevalence of foot abnormalities, although the type and severity of abnormality varied among populations. Of the three populations surveyed by histopathology, the prevalence of chronic laminitis ranged between 40% and 93%. CONCLUSIONS: Foot health appeared to be affected by the environment inhabited by the horses. The observed chronic laminitis may be attributable to either nutritional or traumatic causes. Given the overwhelming evidence of suboptimal foot health, it may not be appropriate for the feral horse foot to be the benchmark model for equine foot health.

Farriery for the hoof with low or underrun heels.

Underrun heels are common and involve hoof capsule distortion in which the horn tubules of the heels undergo bending and lengthening, resulting in decreased strength and functionality. The syndrome varies in clinical presentation, depending on duration, severity of distortion, presence of secondary problems, and presence of lameness. Primary treatment goals are to maintain soundness and functional integrity of the foot and to establish a normal hoof capsule. Resolution of the problem is generally not achieved in horses in a heavy work schedule, and realistic goals in this situation are to maintain function, alleviate lameness, and arrest progression of the distortion.

Farriery for the hoof with a high heel or club foot.

A club foot or flexural deformity may affect a horse at any stage of life from neonate through adulthood. The emphasis of this article is on defining and recommending the appropriate farriery for flexural deformities involving the deep digital flexor tendon and the distal interphalangeal joint. Clinical management of the flexural deformity is influenced by the severity, duration, and etiology of the club foot as well as the degree and source of lameness. Also discussed is the management of mismatched hoof angles, which remains a controversial subject for both farrier and veterinarian.

Mutations in Frizzled 6 cause isolated autosomal-recessive nail dysplasia.

Inherited and isolated nail malformations are rare and heterogeneous conditions. We identified two consanguineous pedigrees in which some family members were affected by isolated nail dysplasia that suggested an autosomal-recessive inheritance pattern and was characterized by claw-shaped nails, onychauxis, and onycholysis. Genome-wide SNP array analysis of affected individuals from both families showed an overlapping and homozygous region of 800 kb on the long arm of chromosome 8. The candidate region spans eight genes, and DNA sequence analysis revealed homozygous nonsense and missense mutations in FZD(6), the gene encoding Frizzled 6. FZD(6) belongs to a family of highly conserved membrane-bound WNT receptors involved in developmental processes and differentiation through several signaling pathways. We expressed the FZD(6) missense mutation and observed a quantitative shift in subcellular distribution from the plasma membrane to the lysosomes, where the receptor is inaccessible for signaling and presumably degraded. Analysis of human fibroblasts homozygous for the nonsense mutation showed an aberrant response to both WNT-3A and WNT-5A stimulation; this response was consistent with an effect on both canonical and noncanonical WNT-FZD signaling. A detailed analysis of the Fzd(6)(-/-) mice, previously shown to have an altered hair pattern, showed malformed claws predominantly of the hind limbs. Furthermore, a transient Fdz6 mRNA expression was observed in the epidermis of the digital tips at embryonic day 16.5 during early claw morphogenesis. Thus, our combined results show that FZD6 mutations can result in severe defects in nail and claw formation through reduced or abolished membranous FZD(6) levels and several nonfunctional WNT-FZD pathways.

Morphometry and abnormalities of the feet of Kaimanawa feral horses in New Zealand.

OBJECTIVE: The present study investigated the foot health of the Kaimanawa feral horse population and tested the hypotheses that horses would have a large range of foot morphology and that the incidence of foot abnormality would be significantly high. PROCEDURES: Abnormality was defined as a variation from what the two veterinarian assessors considered as optimal morphology and which was considered to impact negatively on the structure and/or function of the foot. Fifteen morphometric variables were measured on four calibrated photographic views of all four feet of 20 adult Kaimanawa feral horses. Four morphometric variables were measured from the lateromedial radiographs of the left forefoot of each horse. In addition, the study identified the incidence of gross abnormality observed on the photographs and radiographs of all 80 feet. RESULTS: There was a large variation between horses in the morphometric dimensions, indicating an inconsistent foot type. Mean hoof variables were outside the normal range recommended by veterinarians and hoof care providers; 35% of all feet had a long toe conformation and 15% had a mediolateral imbalance. Abnormalities included lateral (85% of horses) and dorsal (90% of horses) wall flares, presence of laminar rings (80% of horses) and bull-nose tip of the distal phalanx (75% of horses). Both hypotheses were therefore accepted. CONCLUSIONS: The Kaimanawa feral horse population demonstrated a broad range of foot abnormalities and we propose that one reason for the questionable foot health and conformation is lack of abrasive wearing by the environment. In comparison with other feral horse populations in Australia and America there may be less pressure on the natural selection of the foot of the Kaimanawa horses by the forgiving environment of the Kaimanawa Ranges. Contrary to popular belief, the feral horse foot type should not be used as an ideal model for the domestic horse foot.

Postmortal radiographic diagnosis of laminitis in a captive European moose (Alces alces).

A five year-old bull moose (Alces alces) was culled due to chronic hoof overgrowth that required frequent intervention. Radiographic examination revealed changes in phalangeal bone structure usually considered indicative for laminitis in domestic cattle; similar changes were absent in the hooves of a free-ranging moose of similar age. The captive animal had been maintained in exhibits whose flooring were much harder than the soil in natural moose habitat, and on a diet with a high proportion of easily fermentable carbohydrates. These findings indicate that chronic laminitis should be considered as a potential underlying factor for hoof overgrowth, and that measures aimed at reducing the incidence of laminitis in domestic cattle, such as the use of softer flooring and diets with a higher proportion of fibre, might have prophylactic potential in captive wild ruminants.

Conformation of hind legs and lameness in Danish Holstein heifers.

Lameness causes major financial losses and welfare problems in dairy herds. Prevention of foot lesions may suffice in the majority of lameness cases. The objectives of this longitudinal study were to describe the dynamics and associations between abnormal hind leg conformation, asymmetric claws, lameness, and foot lesions in 122 Danish Holstein heifers from an average of 41 d before first calving until dry off or culling. The cattle were housed either in a free-stall system with cubicles or in deep-bedded straw yard. The claws of all cattle were examined on up to 5 occasions. The associations between foot lesions, lameness, symmetry of the claws, shape of the dorsal toe-wall, and the conformation of the hind legs were examined statistically using mixed models. A large proportion (81%) of the heifers had cow-hocked conformation, with wide-based stance, hocks together, and lateral rotation of the foot before calving, and 25% of the heifers had locomotion scores above 2, indicating signs of lameness, before calving. Our results indicate that lameness, abnormal conformation, and lesions acquired precalving persist throughout the first lactation. Thinner cows were more cow-hocked, and cow-hocked cows had a higher frequency of sole hemorrhages. Increased severity of white line lesion was associated with greater claw asymmetry. More severe lameness and sole hemorrhages were found in symmetric claws.

Comparison of stress zones in finite element models of deformed bovine claw capsules.

Pathological claw formations occur subsequent to irregular or prolonged claw trimming periods and as a result of improper flooring. Clinical experience and material testing finds horn of minor quality to be associated with the malformations. Finite element models (FEM) of a flat claw (FC), a contracted claw (CC), and a laminitic claw (LC) were designed from native claw specimens to combine material properties and altered claw geometry for stress analysis. The FEM were created by digitizing the typically deformed exungulated claw capsule by means of computed tomography or digital photography. The derived geometry data were meshed with finite elements and the material properties were attributed. Loading was performed via vertical load vectors according to the suspensory and support apparatus of the bovine digit. All FEM were loaded on soft floors. Loading of the FEM of the FC with 756 N exhibited maximum stress values of 3.32 MPa in the dorsal wall, that of the CC exhibited comparably lower stress of 1.33 MPa in the distal abaxial wall, and the model of the LC showed maximum stress of 4.51 MPa in the region of the dorsal border, all at the same loading. The solar surfaces and the corresponding imprints showed stress concentrations in the palmar aspect of the bulb in the FC, a highly stressed bearing margin of the abaxial wall in the CC, and a diffusely stressed sole and bulb in the LC in contrast to the sound claw models. The FEM of the selected pathological claw forms (FC, CC, LC) calculated high stress zones exactly at locations in the claw wall and sole where clinical experts expect the typical claw lesions for these pathologies. These results were obtained simply by exchanging the outer form of the claw capsules; the method of loading and type of flooring for these pathological models were equivalent to those of the sound FEM. It is highly possible that the stress zones derived from these calculations represent corium compression in reality, and these data support the pathophysiological theory that claw lesions may arise as a consequence thereof.

Cell autonomy of the mouse claw paw mutation.

Mice homozygous for the autosomal recessive mutation claw paw (clp) are characterized by limb posture abnormalities and congenital hypomyelination, with delayed onset of myelination of the peripheral nervous system but not the central nervous system. Although this combination of limb and peripheral nerve abnormalities in clp/clp mice might suggest a common neurogenic origin of the syndrome, it is not clear whether the clp gene acts primarily in the neurone, the Schwann cell or both. In the work described here, we address this question of cell autonomy of the clp mutation through reciprocal nerve grafting experiments between wild-type and clp/clp animals. Our results demonstrate that the clp mutation affects the Schwann cell compartment and possibly also the neuronal compartment. These data suggest that the clp gene product is expressed in Schwann cells as well as neurones and is likely to be involved in direct axon--Schwann cell interactions. Within the Schwann cell, clp affects a myelin-related signaling pathway that regulates periaxin and Krox-20 expression, but not Oct-6.

Injection of corticosteroids, hyaluronate, and amikacin into the navicular bursa in horses with signs of navicular area pain unresponsive to other treatments: 25 cases (1999-2002).

OBJECTIVE: To determine history, clinical and radiographic abnormalities, and outcome in horses with signs of navicular area pain unresponsive to corrective shoeing and systemic nonsteroidal anti-inflammatory drug administration that were treated with an injection of corticosteroids, sodium hyaluronate, and amikacin into the navicular bursa. DESIGN: Retrospective study. ANIMALS: 25 horses. PROCEDURE: Data collected from the medical records included signalment, history, horse use, severity and duration of lameness, shoeing regimen, results of diagnostic anesthesia, radiographic abnormalities, and outcome. RESULTS: 17 horses had bilateral forelimb lameness, 7 had unilateral forelimb lameness, and 1 had unilateral hind limb lameness. Mean duration of lameness was 9.2 months. All horses had been treated with corrective shoeing and nonsteroidal anti-inflammatory drugs for at least 6 months; 18 had previously been treated by injection of corticosteroids and sodium hyaluronate into the distal interphalangeal joint. Fourteen horses had mismatched front feet, and 21 horses had signs of pain in response to application of pressure over the central aspect of the frog. Palmar digital nerve anesthesia resulted in substantial improvement in or resolution of the lameness in all horses. Twenty horses (80%) were sound and returned to intended activities 2 weeks after navicular bursa treatment; mean duration of soundness was 4.6 months. Two horses that received numerous navicular bursa injections had a rupture of the deep digital flexor tendon at the level of the pastern region. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that navicular bursa treatment may provide temporary improvement in horses with signs of chronic navicular area pain that fail to respond to other treatments.

[Case report--polydactyly in a German holstein calf]. / Fallbericht--Polydaktylie bei einem Deutschen Holsteinkalb.

A female German Holstein twin calf showed polydactyly in both front limbs and in one of the hind limbs. In three limbs an additional medial toe was seen. No malformations of the limbs were present in the male twin partner and four maternal half sibs. The analysis of the pedigree revealed that the affected calf had common ancestors. The coefficient of inbreeding of the affected calf was 1.312%. As a monogenic or digenic inheritance was suspected in similar cases, it may be probable that the polydactyly observed here has a genetic background.

Abnormalities of hoof growth and development.

The normal development of the horn capsule (epidermis), with its dermal support (corium), is described. Abnormalities of horn growth may be caused by changes in blood flow (laminitis), the biomechanics of weight bearing, heritable developmental conditions, and other changes of unknown cause.