Morphology of the laminar junction in relation to the shape of the hoof capsule and distal phalanx in adult horses (Equus caballus)

A preliminary case study of the effect of shoe-wearing on the biomechanics of a horse's foot

Horse racing is a multi-billion-dollar industry that has raised welfare concerns due to injured and euthanized animals. Whilst the cause of musculoskeletal injuries that lead to horse morbidity and mortality is multifactorial, pre-existing pathologies, increased speeds and substrate of the racecourse are likely contributors to foot disease. Horse hooves have the ability to naturally deform during locomotion and dissipate locomotor stresses, yet farriery approaches are utilised to increase performance and protect hooves from wear. Previous studies have assessed the effect of different shoe designs on locomotor performance; however, no biomechanical study has hitherto measured the effect of horseshoes on the stresses of the foot skeleton in vivo. This preliminary study introduces a novel methodology combining three-dimensional data from biplanar radiography with inverse dynamics methods and finite element analysis (FEA) to evaluate the effect of a stainless steel shoe on the function of a Thoroughbred horse's forefoot during walking. Our preliminary results suggest that the stainless steel shoe shifts craniocaudal, mediolateral and vertical GRFs at mid-stance. We document a similar pattern of flexion-extension in the PIP (pastern) and DIP (coffin) joints between the unshod and shod conditions, with slight variation in rotation angles throughout the stance phase. For both conditions, the PIP and DIP joints begin in a flexed posture and extend over the entire stance phase. At mid-stance, small differences in joint angle are observed in the PIP joint, with the shod condition being more extended than the unshod horse, whereas the DIP joint is extended more in the unshod than the shod condition. We also document that the DIP joint extends more than the PIP after mid-stance and until the end of the stance in both conditions. Our FEA analysis, conducted solely on the bones, shows increased von Mises and Maximum principal stresses on the forefoot phalanges in the shod condition at mid-stance, consistent with the tentative conclusion that a steel shoe might increase mechanical loading. However, because of our limited sample size none of these apparent differences have been tested for statistical significance. Our preliminary study illustrates how the shoe may influence the dynamics and mechanics of a Thoroughbred horse's forefoot during slow walking, but more research is needed to quantify the effect of the shoe on the equine forefoot during the whole stance phase, at faster speeds/gaits and with more individuals as well as with a similar focus on the hind feet. We anticipate that our preliminary analysis using advanced methodological approaches will pave the way for new directions in research on the form/function relationship of the equine foot, with the ultimate goal to minimise foot injuries and improve animal health and welfare.

Effects of barefoot trimming on hoof morphology

OBJECTIVE

To monitor changes in hoof morphology in response to barefoot trimming.

METHODS

Seven horses were trimmed every 6 weeks according to barefoot trimming principles, which involved levelling the hoof to live sole, lowering the heels, bevelling the toe and rounding the peripheral wall, while leaving the sole, frog and bars intact. A 4-month period was allowed to lower the heels sufficiently to achieve a hoof shape representative of the barefoot trim. This was regarded as the starting point for morphological adaptations in response to maintenance of the trim. Hoof morphology was measured from lateral, dorsal and solar view photographs and lateromedial radiographs taken at 0, 4 and 16 months. Changes from 0 to 4 months represented differences between a natural hoof shape and the trim, while changes from 4 to 16 months represented adaptive effects during hoof growth.

RESULTS

Establishment of the barefoot trim involved significant shortening of the toe, heel and medial and lateral walls, with increases in angulation at the toe, medial and lateral walls, but not at the heel. Maintenance of the trim resulted in a palmar/plantar migration of the heels, with increases in support length, heel angle and solar angle of the distal phalanx (P3).

CONCLUSIONS

Bevelling the toe and engaging the frog and bars in the weight-bearing function of the foot resulted in elevation of the heel angle and solar angle of P3. These changes may be beneficial in treating under-run heels and negative solar plane angulation of P3.

Lung inflammatory response syndrome after cardiac-operations and treatment of lornoxicam

The majority of patients survive after extracorporeal circulation without any clinically apparent deleterious effects. However, disturbances exist in various degrees sometimes, which indicate the harmful effects of cardiopulmonary bypass (CPB) in the body. Several factors during extracorporeal circulation either mechanical dependent (exposure of blood to non-biological area) or mechanical independent (surgical wounds, ischemia and reperfusion, alteration in body temperature, release of endotoxins) have been shown to trigger the inflammatory reaction of the body. The complement activation, the release of cytokines, the leukocyte activation and accumulation as well as the production of several "mediators" such as oxygen free radicals, metabolites of arachidonic acid, platelet activating factors (PAF), nitric acid, and endothelin. The investigation continues today on the three metabolites of lornoxicam (the hydroxylated metabolite and two other metabolites of unknown chemical composition) to search for potential new pharmacological properties and activities.

Variability in the growth patterns of the cornified claw sheath among vertebrates: implications for using biogeochemistry to study animal movement

We review the role of biogeochemical signatures, such as stable isotopes and trace elements, in the cornified claw tissue as a means of studying movement and foraging behaviour of vertebrates because this approach is noninvasive and can capture contemporary and historic signatures. Because biogeochemical techniques are still relatively new in studies of animal movement, we are only beginning to understand how the growth patterns of the cornified claw sheath may affect our ability to interpret the biogeochemical signals in these tissues. To move towards resolving this, we review the morphology of the epidermal cornified claw sheath in several taxa that illustrate substantial variation in growth patterns both between taxa and between individual distinct claw regions. For instance, in mammalian claws, deposition of keratinizing cells from the epidermis is nonlinear because the claw tip is composed of old and new cornified epidermal cells, whereas the cornified blade horn covering the claw’s lateral walls is deposited continuously and without assortment, providing unbroken time-series data. We also consider patterns of growth in mammalian hooves, as well as reptilian, avian, and amphibian cornified claw sheaths, and address the need for expanded research in this field. We conclude this synthesis by describing a noninvasive technique for monitoring growth rates in a model mammal, the American badger ( Taxidea taxus (Schreber, 1777)), and provide guidelines for future sampling of claw keratin, which will improve our ability to back-calculate the time of biogeochemical integration into this tissue.

Effects of hoof shape, body mass and velocity on surface strain in the wall of the unshod forehoof of Standardbreds trotting on a treadmill

The purpose of this work is to investigate the effects of body mass (BM), velocity (V), and hoof shape on compressive surface strains in the wall of the front hoof at the trot. Toe angle (TA), heel angle (HA), toe length (TL), medial and lateral wall length (MWL, LWL) and BM were measured for nine adult, unshod Standardbreds. Five rosette gauges were glued around the circumference of the left forehoof of each animal which was then trotted on a treadmill at a set range of velocities from 3.5 to 7.5 m s−1. Analysis of variance (ANOVA) of principal compressive strainsɛ2at midstance identified that all primary variables (BM,V, TA, HA, etc.) had a significant effect as did the interactions of TA×HA and BM×TA. These significant variables explained over 96% of the variation inɛ2. Multiple regression ofɛ2on these variables gave equations which accurately predictedɛ2within 3%, but the individual coefficients did not accurately describe how each variable affectedɛ2. Further tests using bivariate regression gave equations that enabledɛ2data to be standardized for BM andVat the gauge locations used here. Strainɛ2increased linearly with mass and curvilinearly with velocity (ɛ2∝V+V2), and both caused redistribution of strain to the dorsum and lateral quarter. Variation in each shape variable caused redistribution rather than simple increase or decrease in strains. The primary conclusion with regard to hoof shape is that the effects of change in any one measurement on strain magnitudes are affected by the values of all other measurements. Resolving the interplay among measurements in their effects onɛ2will need a considerably larger sample size than that used here.

Density and morphologic features of primary epidermal laminae in the feet of three-year-old racing Quarter Horses

OBJECTIVE

To quantify the density of primary epidermal laminae (PELs) around the solar circumference and evaluate the relationship between regional PEL density and hoof capsule morphology in horses.

SAMPLE POPULATION

Forefeet from nine 3-year-old Quarter Horse cadavers.

PROCEDURES

Data pertaining to gross features of hoof morphology and PEL variables, including number, density, and distribution patterns around the perimeter of the hoof wall and number of bar PELs, were collected. Tissues of the laminar junction were examined histologically.

RESULTS

No significant differences were found between left and right forefeet with respect to gross hoof morphologic measurements. Mean +/- SD number of PELs, including those at the bars of the hoof, was 551 +/- 30. Primary epidermal laminar density in the toe was significantly higher, compared with that in the quarter and heel regions, and was higher on the lateral aspect of the foot, compared with the medial aspect. Feet were significantly wider on the lateral aspect of the foot, compared with the medial aspect, as measured across the widest point of the solar surface. Histologic examination revealed atypical laminar morphology at the toe.

CONCLUSIONS AND CLINICAL RELEVANCE

Variations were detected in PEL density and morphology around the solar circumference of hooves from 3-year-old racing Quarter Horses. A better understanding of relationships between laminar density, laminar morphology, and gross morphology of the hoof capsule in different populations of horses may aid practitioners in diagnosis and treatment of disease involving the hoof wall in horses.

Changes in shape of the Standardbred distal phalanx and hoof capsule in response to exercise

The aims of this study were to determine whether the equine distal phalanx changes in shape in response to exercise and to relate any osseous changes to those in the hoof capsule. Eighteen mature Standardbred horses were randomly divided into exercise and control groups. Exercised horses were jogged on a straight track at individual mean speeds between 4 and 8 m s− 1for 10–45 min, 4 days per week for 16 weeks. Both groups were similarly shod and pastured on the same field. Before and after the training period, each horse had digital photographs and magnetic resonance images (MRI) made of the right forehoof. Five linear measurements of the distal phalanx were recorded from the MRI and 24 measurements of the hoof capsule were made on the digital photographs. Small but significant changes in bone width (P = 0.039) were found in the controls and in two sagittal measurements of bone length (P = 0.039, 0.001, respectively) for the exercise group. These changes were slight and did not correlate with changes in shape of the hoof capsule, suggesting that the bone acts as a stable platform for supporting the capsule and withstanding loads.

Fetal development of the segment-specific papillary body in the equine hoof

Fetal development of the unique papillary body and its localized peculiarities in the equine hoof are described based on the study of 51 fetuses, nine newborn foals, and five adult horses. The shape and dimensions of the dermal papillae and lamellae have a formative influence on the structure and physical quality of the corneous hoof capsule with its horn tubules and lamellae. The size and arrangement of these horn structures determine the mechanical quality of hoof horn. Proper horn quality is a prerequisite for the various functions of the hoof capsule, such as protecting the living dermis supporting the hoof capsule, shock absorption, and formation of the suspensory apparatus of the distal phalanx. Development of the segment-specific papillary body is initiated by the increasing mitotic activity of the epidermal cells invaginating the dermal surface, thus forming dermal microridges. These microridges are transformed into single dermal papillae, which are arranged in rows, or enlarged to become primary and secondary dermal lamellae. The formation of a segment-specific papillary body enables the increasing keratinization ratio in the hoof epidermis and the formation of the characteristic tubular and lamellar horn responsible for the special mechanical properties of hoof horn.

Horse hooves and bird feathers: Two model systems for studying the structure and development of highly adapted integumentary accessory organs--the role of the dermo-epidermal interface for the micro-architecture of complex epidermal structures

Accessory organs of the integument are locally modified parts of the potentially feather-bearing skin in birds (e.g., the rhamphotheca, claws, or scales), and of the potentially hairy skin in mammals (e.g., the rhinarium, nails, claws, or hooves). These special parts of the integument are characterised by a modified structure of their epidermal, dermal and subcutaneous layers. The developmental processes of these various integumentary structures in birds and mammals show both similarities and differences. For example, the development of the specialised epidermal structures of both feathers and the hoof capsule is influenced by the local three-dimensional configuration of the dermis. However, in feathers, in contrast to hooves, the arrangement of the corneous cells is only partially a direct result of the particular arrangement and shape of the dermal surface of the papillary body. Whereas the diameter of the feather papilla, as well as the number, length, and width of dermal ridges on the surface of the feather papilla influence the three-dimensional architecture of the feather rami, there is no apparent direct correlation between the dermo-epidermal interface and the development of the highly ordered architecture of the radii and hamuli in the feather vane. In order to elucidate this morphogenic problem and the problem of locally different processes of keratinisation and cornification, the structure and development of feathers in birds are compared to those of the hoof capsule in horses. The equine hoof is the most complex mammalian integumentary structure, which is determined directly by the dermal surface of the papillary body. Perspectives for further research on the development of modified integumentary structures, such as the role of the dermal microangioarchitecture and the selective adhesion and various differentiation pathways of epidermal cells, are discussed.