Consistent detection of bovine papillomavirus in lesions, intact skin and peripheral blood mononuclear cells of horses affected by hoof canker.

REASONS FOR PERFORMING THE STUDY: Equine hoof canker is a chronic proliferative pododermatitis of as yet unknown aetiology. Like equine sarcoid disease, canker is a therapy-resistant disorder characterised by hyperkeratosis, acanthosis and a marked tendency to recur. HYPOTHESIS: There is an association of sarcoid-inducing bovine papillomaviruses of types 1 and 2 (BPV-1, BPV-2) with hoof canker disease. METHODS: Using PCR-based techniques, we assessed canker tissue, intact skin and/or peripheral blood mononuclear cells (PBMCs) of 25 canker-affected horses for the presence of sarcoid-associated BPV-1 and -2. RESULTS: Conventional PCR revealed BPV-1/-2 DNA in 24/24 canker, 12/13 skin and 10/11 PBMC DNA isolates. Using inverse PCR, full-length BPV episomes were detected in 1/5 canker specimens. Sequencing of viral early and late genes amplified from canker, intact skin and PBMC DNA of 2 cases revealed an overall identity of 98% to BPV-1. Viral DNA loads amounted to ≤16 copies per cell in canker tissue and intact skin, and to ≤0.35 copies per PBMC, as determined by quantitative PCR. Using RT-PCR, the viral major oncogene E5 was shown to be transcribed in 2/4 canker tissue specimens and 5/7 PBMC isolates. Immunocapture PCR from 7 canker and 6 skin extract supernatants revealed capsomere-associated viral DNA in one canker and one skin sample. Hoof tissue, skin and PBMCs collected from 13 individuals with no signs of canker or BPV-related malignancies scored negative throughout the experiments. CONCLUSION: These findings suggest that the observed presence of BPV-1/-2 in canker-affected horses is not coincidental but indicative of an active contribution to hoof canker disease. POTENTIAL RELEVANCE: The use of antivirals and/or immune modulators may help improving canker therapy.

Thirty-two component finite element models of a horse and donkey digit.

REASONS FOR PERFORMING STUDY: The finite element (FE) method is the most powerful modelling technique available to explicate the biomechanics of the digit. It has already proved to be of high value in human podiatry. However, accurate models of the complex anatomy of the horse and donkey digit are currently lacking. OBJECTIVES: To develop FE models of the horse and donkey digit from computed tomography data, including all functionally relevant anatomy, and to perform simulations to replicate prestrain in the flexor tendons and quasistatic weightbearing. METHODS: Computed tomography data of the front right digits were obtained under general anaesthesia. The anatomy was rationalised into 32 functional components. The FE models were generated using a forward engineering technique. Linear or nonlinear material properties were applied according to published data. Prestraining of the flexor tendons was achieved by z-direction displacement, and loading by the application of 1 x body mass. RESULTS: The resultant FE models comprised over 10(6) elements. Z-direction displacement of the digital flexor tendons to compensate for general anaesthesia relaxation gave von Mises stress levels up to 134 MPa for the deep and 0.56 MPa for the superficial in the horse and 0.78 MPa and 0.27 MPa in the donkey, respectively. Weightbearing resulted in capsular deformation patterns consistent with in vivo observations, and maximum stress levels of 1.46 MPa for the horse and 0.89 MPa for the donkey. CONCLUSION: These high resolution FE models could give new insight into the biomechanics of the equid digit and provide new data regarding stress and strain levels within the tissues of the digit that are unobtainable by other means. POTENTIAL RELEVANCE: Application of the FE modelling technique could enable investigation of the biomechanics of orthopaedic problems and may provide a mechanistic basis for enhanced preventative and remedial management and treatment.

Development of a twenty-one-component finite element distal hind limb model: stress and strain in bovine digit structures as a result of loading on different floorings.

Finite element modeling is a unique way of introducing technical and material research into medical science. A bovine distal hind limb was scanned using computed tomography for geometric image capture and the data were subsequently divided (segmented) into 4 tissue types: bone, bone marrow, soft tissue, and the horn capsule. Material data from previous studies were integrated into the model. Flexor tendons were assembled as longitudinal structures starting at their cross-sectional areas at the height of the metatarsophalangeal joint, proceeding in the plantaro-distal direction and meeting the distal phalanx at the tuberculum flexorium. Three different flooring situations (full support floor, bearing weight in the abaxial half of the lateral claw and in the dorsal halves of both claws, respectively) were created to evaluate the effects of loading. Full support resulted in von Mises stress levels between 3.5 and 1.5 MPa for the osseous structures and some regions of the segmented soft tissue; stress patterns in the bulb and sole of the claw capsule (1.5 MPa) and in the floor (0.5 MPa) were similar to pressure plate data in vivo and in vitro, with corresponding strain values of 2.4%. Reduced support resulted in higher stresses (up to approximately 8 MPa) in bones, claw capsules, and tendons; high strains ( approximately 11%) were found in the soft tissue, depending on how the floor was constructed. Although the models may still be anatomically improved, stress and strain calculations are possible with results comparable to related research, and the model shows interaction between the 2 digits. This possibly will help with further understanding of the biomechanical function of this 2-digit structure. With respect to clinical interpretation, reduced support to the bovine hind limb increases focal stress peaks in the different tissues, which may indicate a location of potential injury.

Anatomical features of the carpal flexor retinaculum of the horse.

This study aims to elucidate the topographical anatomy of the carpal flexor retinaculum or palmar anular carpal ligament (PACL) in the horse. Ten specimen of the carpus of five healthy horses were studied by dissection in layers. Slices of 5 mm in thickness facilitated observation of the soft tissues. The superficial layer of the PACL subdivides into five compartments: one for the palmar nerve and the arterial and venous branches, one for only the radial artery, one for the radial vein, and one for the tendon of the radial carpal flexor muscle, and finally for the deep layer that supports all tendinous structures located palmar to the carpus, as well as the median artery and palmar medial nerve. The sections of the segmented PACL that are affected by carpal canal syndrome may vary with the aetiology of the space-occupying process. Precise anatomical knowledge of the structures may help in understanding the pathological processes and determining the most appropriate therapy.

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.

Slatted floors and solid floors: stress and strain on the bovine hoof capsule analyzed in finite element analysis.

An established finite element model of a bovine claw was used to compare mechanical stress levels in a loaded model claw on different types of flooring. The following situations were compared: a claw standing on a solid floor, a claw standing on the edge of a short tie stand, and claws standing on slatted floors with slats of 28 and 40 mm (wide) running parallel and perpendicular to the claw axis. Finite element analysis allowed visualization of stress peaks seen predominantly in the weight-bearing border of the dorsal abaxial wall and of the bulbar region and in the proximal axial wall. Maximum stress values of 13 MPa were found in the model claw loaded on the solid floor and values of 18 to 22 MPa were seen in the model claw loaded on the edge of the solid floor. On slatted floors, stresses increased in the situation in which the claw was not supported under the abaxial wall. Comparison between the other slatted floors showed little difference in amounts of mechanical stress. A clear distinction was detected between the solid floor with full claw contact and the slatted floors. From the point of view of the mechanical stress seen in finite element analysis, a large contact area between claw and floor, as seen in the solid surface floor, is preferable. When use of slatted floors is unavoidable, direction of the slats should run perpendicular to the direction of the walkway to prevent even more mechanical impact in certain footing situations.

A finite element model of the bovine claw under static load for evaluation of different flooring conditions.

AIM: To create a computer-based finite element (FE) model of the bovine claw and to use finite element analysis (FEA) to estimate stress and deformation of a physiologically-shaped model claw under static load, to visualise potential material weakness and to evaluate the effect of different flooring conditions. METHODS: Model geometry was derived using digitalised images from a recently trimmed, sound, hind claw from a 4-year-old Austrian Fleckvieh cow. Material properties of bovine claw horn were defined from preliminary investigations and recently established material data, using a modulus of elasticity from 200 to 600 N/mm2. Meshing of the model was performed with 42,127 elements based on 116,141 nodes. Loading of the model was defined at 756 N per claw on a hard and soft surface. RESULTS: The FE model of the bovine claw under a load of 756 N showed only minimal deformation, most of which took place at the axial wall. Highest stresses were evident in the proximal axial wall, the outer edge of the weight-bearing surface and under the heels. The claw-floor contact image showed a pressure distribution resembling the distal rim of the claw wall. On the hard surface, the maximum stresses were three times higher than those on the soft surface. CONCLUSIONS AND CLINICAL RELEVANCE: FEA allowed visualisation of the effects that loading on different floor surfaces have on the biomechanics of the claw. Uneven preparation of the claw sole resulted in high stresses at and close to irregularities of the sole. Consequences were more severe on harder flooring. The model supports the hypothesis that mechanical factors play a substantial role in the pathogenesis of claw lesions.

Elastic properties of hoof horn on different positions in the bovine claw.

Hind claws of 15 adult, sound Fleckvieh cows were used for material analysis. The elastic modulus was tested in tension tests according to EN ISO 527 and ASTM D 638-03 at a universal material testing machine. Samples were taken from different segments of the bovine claw to find the differences in material properties. Samples orientation was parallel to the horn tubules and transversal, respectively. Dry matter of the test samples was determined at the time of testing. Elastic modulus values were highest with mean = 659.7 N/mm2 at the dorsal wall. Values dropped axial to 416.3 N/mm2, abaxial to 343.9 N/mm2 for longitudinal (parallel) samples and to 433.1 N/mm2 for transversal samples. The elastic modulus of the sole segment was found to be 172.1 N/mm2. No difference was calculated neither between right and left feet, lateral and medial claws, nor between longitudinal and transversal samples.

Finite element analysis (FEA) as a model to predict effects of farriery on the equine hoof.

A finite element (FE) hoof capsule was built as a small, symmetrical forelimb hoof on IDEAS* as a model for calculation and visualisation of stress and displacement of the equine hoof capsule. The model's loading was performed according to the suspension of the coffin bone within the hoof wall (pulling force) and over the sole and frog (compressing force) with a total of 3000 N. Restraints of the model's ground nodes and surface wall nodes were defined for simulation of 4 shoeing situations: a regular horseshoe, a horseshoe with a toe clip, a horseshoe with regular side clips and a horseshoe with a toe clip and more caudally-placed side clips, all fixed to the hoof capsule with 3 nails on each side and each calculated in a tense and a loose nailed condition. Von Mises stresses were taken ranging from 1.22 N/mm2 in the weightbearing border of the side clip shoe fixed loosely to the capsule up to 16.67 N/mm2 in the hoof horn material surrounding the third nail. Further high stress zones were calculated in the proximal dorsal wall, the distal heel and the lateral hoof wall. Displacement values were taken showing movements of hoof wall, sole and frog according to the shoeing conditions. Maximal displacement was calculated in the hoof capsule shod with a regular horseshoe without a clip. Minimal displacement was found in the capsule with a toe clip and 2 side clips placed behind the 3rd nail. All models showed higher displacements when calculated with a loose nail fixation. Validation of the detailed features of the models is not yet possible. Finite element analysis (FEA) can be used practically to predict influences of various farrier techniques on the equine hoof in order to avoid possible harm to horses' feet in field studies.

The effect of flat horseshoes, raised heels and lowered heels on the biomechanics of the equine hoof assessed by finite element analysis (FEA).

The biomechanical effects of lowering and raising the heels were studied using a finite element (FE) computer model of the equine hoof capsule consisting of 18,635 finite elements. A static load of 3000 N was distributed to nodes of the inner hoof wall (80%) according to the suspension of the coffin bone, 20% loaded sole and frog. When loaded the FE hoof capsules showed the following deformations: the proximal dorsal wall moves back, the quarters flare to the side and sole and frog perform a downward movement. Stresses are high in the material surrounding the quarter nails, in the heels and in the proximal dorsal wall. Three types of horseshoes were simulated, a regular shoe with flat branches, a shoe with 5 degrees raised heels and a shoe with 5 degrees lowered heels. Raising the heels resulted in significantly (P < 0.05) low stress and displacement values. The lowered heels model calculated highest stress and displacement values and the results of the FE model with the regular horseshoe were found in between.

[Use of tempered, particle-reinforced aluminum horse shoes in sport horses under field conditions]. / Die Erprobung von getemperten, partikelverstärkten Aluminiumhufbeschlägen beim Sportpferd im Feldversuch.

The use of handmade particulate reinforced alloy horseshoes (MMC metal matrix composites) was tested in a field study on 15 riding and draught horses. All horseshoes have been tempered after having been manually forged and tested concerning their surface imperfection. Forging temperature ranged between 350 degrees and 420 degrees C. Horseshoes in series A consisted of particulate reinforced wrought alloy (22% Al2O3 in alloy matrix). 11 shoeing periods with a duration of mean = 49.7 days (sd = 13.6) were evaluated. Horseshoes in series B consisted of particulate reinforced foundry alloy (20% SiC in alloy matrix), 5 shoeing periods were evaluated with a duration of mean = 45.4 days (sd = 7.9). Series C tested horseshoes made of particulated reinforced coextruded wrought alloy evaluating 6 shoeing periods with a duration of mean = 49.2 days (sd = 18.7). Service of the tempered particulate reinforced alloy horseshoes was significantly higher compared to untempered alloy horseshoes. Mechanical and forging properties of tempered particulate reinforced alloy are satisfactory. Service is only suitable for riding horses but not for draught horses.

Elastic modulus of equine hoof horn, tested in wall samples, sole samples and frog samples at varying levels of moisture.

The elastic (E-) modulus of hoof horn samples as a function of moisture content was determined from different segments of the equine hoof. 110 hoof horn specimens with different pigmentation taken from six adult warm-blooded horses with no obvious pathological changes within t he foot were used for the 177 tension and bending tests which were performed in accordance with ASTM D 5026, ASTM D 5023 and DIN 53.457. E-moduli were determined under physiological conditions with mean 761.8, SD +/- 295.4 N/mm for dorsal wall samples, 708 +/- 280.4 N/mm2 for lateral wall samples, 230 +/- 92.4 N/mm2 for sole horn and 9.9 +/- 0.6 N/mm2 for frog horn. Dorsal wall and lateral wall did not differ significantly. E-moduli of the various hoof horn segments differ significantly when tested under physiological moisture. The physiological moisture content also varies significantly between the segments: wall samples mean 22.7 +/- SD 3.4%, sole samples 31.5 +/- 3.1%, frog samples 34.6 +/- 3.3%. In contrast, the E-moduli and the moisture contents of the various segments were approximately identical, when tested after drying at 65% humidity over 6 days.