Tubule density of the stratum medium of horse hoof

The number of tubules/mm2 (tubule density) of horse hoof horn was quantified in samples taken from the left forefeet of 8 randomly selected slaughterhouse horses in order to establish the normal tubule density characteristics at the midline dead centre (MDC) for the stratum medium of horse hoof. In the past the measurement of tubule distribution within the hoof has lacked objectivity. The horse hoof tubule density results are compared to a recent objective study carried out on pony hoof. A similar 4 zone pattern of tubule density was observed, although the precise zonal boundaries and tubule density values differed to those found for pony hoof. There were significant differences in tubule density between zones. Comparison with pony hoof revealed significant tubule density differences in zones 1, 2 and 4; however, there was no significant difference in zone 3. The existence of a 4 zoned pattern of tubule density for horse hoof, as for pony hoof, has been confirmed.     

Variation in surface strain on the equine hoof wall at the midstep with shoeing, gait, substrate, direction of travel, and hoof shape

Objectives were to examine the deformation of the healthy equine front hoof during locomotion, by recording strains on its outer surface, and to test whether its mechanical behaviour is significantly altered under different locomotory conditions and variation in hoof shape. Strains were recorded in vivo from 5 rosette gauges around the circumference of the right forehooves of 12 horses. The magnitudes and orientations of principal strains at the midstep were compared statistically for different conditions of shoeing (shod vs. unshod), gait (walk vs. trot), substrate (treadmill vs. ground), and direction of travel (straight, right turn, left turn). Principal strains were regressed on 4 variables describing hoof shape-toe length, toe angle, and medial and lateral wall angle--to describe their contribution to variations in strain and hoof deformation. Shoeing did not essentially change the magnitudes of the larger, compressive principal strain, but caused some strain reorientation. Shoes decreased the variation in strains indicating that they tend to stabilise the deformation of the hoof. Strain magnitudes were significantly greater at trot than walk, but there was little change in orientation indicating that the general pattern of deformation of the hoof is constant between these 2 gaits. Strain patterns showed small but significant differences between locomotion on the treadmill and on ground, with the differences being more apparent at the toe than at the sides of the hoof. When turning, the quarter on the inside of the turn experienced 40% more strain than during straightline motion, while strain was similarly reduced on the opposite quarter. Strain magnitudes increase with toe length and toe angle, but were inversely proportional to medial and lateral angles. The change with toe length correlated with the range of body size of the animals in the sample. The change with toe angle was contrary to that found in in vitro tests. The change with medial and lateral angles indicated that hooves with more upright quarters are stiffer and possibly provide less impact absorption.     

Exploring the possible functions of equine hoof wall tubules

Possible functions of equine hoof wall tubules were investigated in this study. Hydration tests were conducted on blocks of hoof wall tissue in order to test the hypothesis that hollow tubules facilitate the conduction of water vapour distally. Although water loss or gain was inhibited through the outer wall surface, the increase in surface area provided by medullary spaces was ineffective in facilitating hydration through the face with exposed tubule ends. Rather, hollow tubules appear to allow for a higher dehydration rate through their exposed ends. Analysis of medullary space indicates that the presence of these voids does not provide either a significant increase in flexural stiffness, or a decrease in thermal conductivity. These findings suggest that nonmechanical roles of hoof wall tubules are unlikely and, therefore, the hollow nature of tubules may be a reflection of manufacturing constraints in producing keratin fibres at steep angles to the coronary border.     

A permeability barrier in the dorsal wall of the equine hoof capsule

The permeability barrier in the dorsal wall of the equine hoof capsule was studied by means of horseradish peroxidase (HRP) in 0.9 N saline solution as a water soluble tracer. Section were treated with 3'3'-diaminobenzidine tetrachloride (DAB) and before dissection the quality of the horn of feet from 10 horses was assessed and given a subjective grade as either good or poor. Blocks of tissue from each horse were left in either an oven at 60 degrees C or in water for 2 weeks before treatment in HRP, sectioning and DAB solution. Regions observed were i) outer surface, ii) outermost layers of the horn, iii) cut edge of the outer layer, iv) inner layer of horn, v) cut edge of the inner layer and vi) laminae. Horn deemed to be normal horn and of good 'quality' showed very slight penetration of HRP 3-5 cell layers deep in the outer layer. The cut edge of the outer layer of the wall of the 'normal' horn also showed minimal penetration of HRP through the intercellular spaces. The cut edge of the inner layers of the wall of normal, good quality horn showed penetration of the tracer up to 20 cell layers deep, with HRP in both the intercellular spaces and within the cells. In contrast, sections of horn from horses with brittle feet showed deep cracks in the outer surface into which the HRP had penetrated. Good quality horn showed no change in the position of the permeability barrier after soaking in water for 14 days, but the brittle horn showed an increase in permeability to HRP. In brittle horn, reaction product was seen deep within the section in the intercellular spaces of the intertubular horn only. Placing horn in an oven had no effect on the permeability barrier. The permeability barrier of the dorsal wall of the equine hoof capsule differs with the layer of the wall. Horn considered to be of poor quality had a weaker permeability barrier than horn of good quality.     

Finite element analysis of static loading in donkey hoof wall

A finite element model of donkey hoof wall was constructed from measurements taken directly from the hoof capsule of the left forefoot. The model was created with a 2 mm mesh and consisted of 11,608 nodes. A linear elastic analysis was conducted assuming isotropic material properties in response to a 375 newton (N) load, to simulate static loading. The load was applied to the wall via 400 laminae in order to simulate the way in which the pedal bone is suspended within the donkey hoof capsule. Displacement, stress concentration, principal strain, and force distribution across the hoof wall were evaluated. The hoof wall model revealed loading responses that were in broad agreement with previously reported in vivo and modelled observations of the equid hoof. Finite element analysis offers the potential to model hoof wall function at the macroscopic and microscopic level. In this way, it could help to develop further our understanding of the functional relationship between the structural organisation and material properties of the hoof wall.     

Telemetric measurements of strain in the metacarpus of the horse: a pilot study

The advances made by the use of a telemetric system in the study of bone strain in a free-moving horse are reported. A rosette strain gauge was bonded to the craniomedial aspect of the metacarpus of the horse. Attachment of a miniature FM transmitter to lead wires facilitated telemetric transmission of of resistance changes which corresponded to limb movement. During 3 different gaits, the trace pattern remained similar, although frequency and amplitude varied. The tracings were similar to those reported in other species in which nontelemetric transmission was used.     

In-shoe foot force sensor to assess hoof balance determined by radiographic method in ponies trotting on a treadmill

The oxygen carrying capacity of dilute solutions of hemoglobin from normal human adults was examined, by using the above indicated Oximeter. The results show that, if the pO2s are compared with those drawn from the Oximeter-539 WTW (a simpler instrument) carrying the same oxygen electrode, there is a good correspondence between the data drawn from both the instruments. The advantage of the former is that pO2s are measure in mBr, whereas the latter measures the oxygen of the aqueous solutions in mg/l; then mg must be converted into Torr pO2. Since both instruments are usually employed in the oxygen measurement of waste waters of earth, another conclusion is that their sensitivity also allows the use in the bio-medical (and zoological) field. In fact, the data obtained agree with those of recent literature on the subject, which are mainly drawn from automated and sophisticated apparatuses specifically built at this purpose.     

混合颗粒体光弹力链定量提取方法

岩土工程和采矿工程涉及大量的颗粒物质科学和技术难题,定量识别和提取光弹试验颗粒体系的力链网络结构和分布特征,对于认识和掌握其内部细观力学机理和研究宏观力学行为至关重要.采用彩色梯度均方值(G²)算法,建立了不同粒径的圆形颗粒和方形颗粒的接触力(F)和G²的关系;基于数字图像处理技术,提出了识别和区分图像中不同粒径圆形颗粒和方形颗粒的方法,获得了光弹图片中力链网络结构和力链分布方位.以煤矿综放开采为实例,对所提出的力链定量提取方法进行了验证分析,清晰揭示了综放采面矿压形成机理和本质特征.研究表明:单颗粒的F值与G²呈单调递增关系,且粒径越大,F随G²值的增长速度越快;颗粒体系接触力集中分布在0.5相似文献   

Effects of season and diet on tensile strength and mineral content of the equine hoof wall

Studies evaluating nutritional and seasonal influences on hoof strength and composition in horses, as well as the scientific justification for feeding supplements to improve hoof quality, are lacking. The horseman and veterinarian need controlled studies in this area to make informed decisions. This project quantified, in 2 trials, relative elasticity, tensile strength, % moisture, and mineral composition of hooves of 48 mature Thoroughbred mares maintained on different nutritional/management regimens, sampled quarterly over 12 month periods. Tensile strength was positively associated with sulphur content. Per cent moisture was not significantly associated with tensile strength, relative elasticity, or mineral content measures. Results indicated that both seasonal trends and nutritional regimes greatly affected hoof wall strength and mineral composition.     

混合型应力强度因子的光弹性多参数测定

提高裂纹尖端应力强度因子值的计算精度,对于准确分析受力结构的起裂条件和破坏模式具有重要意义.本文采用3D打印技术获得了不含残余应力的平板模型,高精度打印预置裂纹避免了传统加工过程产生残余应力的缺点;综合考虑奇异场和非奇异场对裂纹尖端区域应力场的影响,引入远场边界控制的三个常数项应力,提出了光弹性多参数法;采用三点弯曲试验,运用最小二乘法计算了不同载荷下纯I型和I-Ⅱ混合型应力强度因子值,并与理论解对比分析.结果表明:对于纯I型应力强度因子,计算结果的平均误差为6.1%,对于I-Ⅱ混合型应力强度因子,计算结果的平均误差分别为6.4%和5.5%,多参数法与理论解相比较小的计算误差验证了该方法的可靠性和准确性,可为精确计算应力强度因子的光弹性实验研究提供借鉴.     

Fluorescent speckle microscopy, a method to visualize the dynamics of protein assemblies in living cells

Fluorescence microscopic visualization of fluorophore-conjugated proteins that have been microinjected or expressed in living cells and have incorporated into cellular structures has yielded much information about protein localization and dynamics [1]. This approach has, however, been limited by high background fluorescence and the difficulty of detecting movement of fluorescent structures because of uniform labeling. These problems have been partially alleviated by the use of more cumbersome methods such as three-dimensional confocal microscopy, laser photobleaching and photoactivation of fluorescence [2]. We report here a method called fluorescent speckle microscopy (FSM) that uses a very low concentration of fluorescent subunits, conventional wide-field fluorescence light microscopy and digital imaging with a low-noise, cooled charged coupled device (CCD) camera. A unique feature of this method is that it reveals the assembly dynamics, movement and turnover of protein assemblies throughout the image field of view at diffraction-limited resolution. We found that FSM also significantly reduces out-of-focus fluorescence and greatly improves visibility of fluorescently labeled structures and their dynamics in thick regions of living cells. Our initial applications include the measurement of microtubule movements in mitotic spindles and actin retrograde flow in migrating cells.     

Effect of supplementary dietary biotin on hoof growth and hoof growth rate in ponies: a controlled trial

The effect of dietary biotin supplementation, at a dose rate of 0.12 mg/kg bwt, on growth and growth rate of the hooves of 8 match-paired poines was investigated in a controlled feeding trial. Treatment animals had a mean hoof growth at the midline dead centre of the hoof capsule of 35.34 mm after 5 months of biotin supplementation compared to control animals 30.69 mm (P < 0.05). Comparison of regression analysis also showed that biotin supplementation produced a significantly higher (P < 0.02) growth rate of hoof horn in this trial. Treatment animals had a 15% higher growth rate of hoof horn and 15% more hoof growth at the midline dead centre, after 5 months of biotin supplementation compared to control ponies. No differences were found between feet for growth of horn, but the older animals in the trial had significantly lower hoof growth (P < 0.05) than the remaining poines.     

Noninvasive, real-time method for the examination of thymidine uptake events--application of the method to V-79 cell synchrony studies

Protein GPI anchors are ubiquitous in eukaryotic cells. More than 50 mammalian proteins are anchored to the membrane via GPI. GPI anchoring is a posttranslational modification occurring in the endoplasmic reticulum where preassembled GPI anchor precursors are transferred to proteins bearing a C-terminal GPI signal sequence. The GPI anchor precursors are synthesized in the endoplasmic reticulum by sequential addition of sugar and other components to phosphatidylinositol. More than ten genes participate in this biosynthetic pathway, eleven of the mammalian genes having been cloned by means of complementation of mutant cells that are defective in this pathway or based on sequence homology to previously cloned yeast counterparts. A somatic mutation in one of those genes, PIG-A, involved in the first reaction step, is responsible for the hemolytic disease, paroxysmal nocturnal hemoglobinuria.     

Identification of a granulocytic Ehrlichia strain isolated from a horse in Switzerland and comparison with other rickettsiae of the Ehrlichia phagocytophila genogroup

This case report describes a 12-year-old Arabian mare with granulocytic ehrlichiosis. Clinical signs included fever, apathy, anorexia, icterus, limb edema, and reluctance to move. Examination of buffy coat smears revealed Ehrlichia organisms in neutrophils and eosinophils. A band of 1,428 bp was amplified from DNA of leukocytes via nested PCR and was identified as part of the Ehrlichia 16S rRNA gene. It differed from the gene sequences of Ehrlichia phagocytophila and E. equi at two and three positions, respectively. Interestingly, the nucleotide sequence of the 16S rRNA was 100% identical to that of the agent of human granulocytic ehrlichiosis.     

The distribution of Anoplocephala perfoliata in the intestine of the horse and associated pathological changes

The intestinal tracts of 130 horses were examined for infection with Anoplocephala perfoliata at necropsy. Fifty horses (38.5%) harboured the tapeworm, and the site of attachment of each worm was recorded using predetermined anatomical landmarks. The worms were attached in four regions of the gastrointestinal tract: 17% of the worms were found at the ileocaecal junction, 81% on the caecal wall, 1.7% in the terminal ileum and 0.2% in the ventral colon. The severity of lesions produced at the sites of attachment was related to the number of worms attached. Due to the small area of the ileocaecal junction, worms at this site were attached in close proximity, resulting in more severe lesions. The major features of the lesions included ulceration, diphtheritic membranes and thickening of the mucosa, submucosa and lamina propria. There was an increase in the number of eosinophils and a decrease in the number of lymphocytes present at the sites of lesions.     

A method of signal processing in motion analysis of the trotting horse

The aim of this paper is to present a method of signal processing necessary for motion analysis in the trotting horse. Motion analysis is widely used to assess lameness in horses. By definition, lameness in trot is present if the movements during the stance phases of both fore or hind limbs differ. The motion of the horse is recorded using a system for motion analysis (Selcom, 1983, SELSPOT II User Manual, Pad Nr. 6710) and the vertical motion of the head during both stance phases is compared. The symmetry is analyzed comparing the values of the Fourier coefficients. Additional head movements are 'single events' and present a problem. In this article we propose a mode of data processing using a system matched filter that neglects the nonperiodic additional movements and allows calculation of the representative Fourier coefficients. In comparison with a filtering method previously used in motion analysis this method is proved to be advantageous, as the precision of symmetry comparison increases.     

Fatal accident to a horse from a narrow transverse beam in the box door

It is reported on the fatal accident of a horse due to a cross-beam too low above the door of the stable, in which the animal suffered several skull fractures and a tear of the musculus longus capitis from the base of the skull. The aim of this article is, to supply a contribution to the establishment of minimal requirements for the housing of horses, in this case for the request of the minimum height of stable doors and ceilings as well as for constructions on horse transporters. On the grounds of this example, the natural behaviour of horses is discussed at the hand of the literature and the efforts are shown to improve the existing inadequacies in the housing and transport of horses with regard to the judicial situation. In the light of section 2 of the animal protection law, as to the construction of horse stables the importance is especially emphasized to consider the panic behaviour in connection with abrupt flight reactions as physiologic in the prevention of accidents.