An autoradiographic study of equine hoof growth

Influences of the seasons of the year and physiographic regions on the levels of calcium, copper and zinc in the hoof capsule of foals pre and post-weaning raised in native pasture

This study evaluated the levels of Ca, Cu and Zn in the hoof of Criollo foals, pre and post-weaning, correlating them with the concentrations of these inorganic chemical compounds in soil and pasture in the different seasons of the year. We used 41 pre-weaning foals and 28 post-weaning foals. Seventeen forage samples were collected in four seasons, later 10 soil samples per property in five distinct physiographic regions (Santa Maria, Dilermando de Aguiar, Jaguarão, Arroio Grande and Pelotas). There was variability in Ca, Cu and Zn concentrations in the hoof foal between distinct physiographic regions (P < 0.05), and between seasons. There was no association of pre-weaning and post-weaning Ca levels with forage in the different physiographic regions. The concentrations of Cu and Zn showed positive association (R = 0.69, 0.43; P < 0.05) with the native pastures in the different physiographic regions in pre-weaning. In post-weaning, only Cu was positively associated (R= 0.74; P < 0.05). Different season and physiographic regions influence the levels of Ca, Cu and Zn in the hoof capsule and native pasture during the pre and post-weaning stages.

The sandwich structure of keratinous layers controls the form and growth orientation of chicken rhinotheca

The upper beak bone of birds is known to be overlain by the rhinotheca, which is composed of the horny sheath of keratinous layers. However, the details of the structure and growth pattern of the rhinotheca are yet to be understood. In this study, the microstructure of the rhinotheca from chicken specimens of different growth stages (ranging from 1 to ~ 80 days old) was analyzed using a combination of thin section and scanning electron microscopy observations, and small-angle X-ray scattering analysis. We found that the rhinotheca comprises three different layers - outer, intermediate, and inner layers - throughout its growth. The outer layer arises from the proximal portion of the beak bone and covers the dorsal surface of the rhinotheca, whereas the intermediate and inner layers originate in the distal portion of the beak bone and underlie the outer layer. This tri-layered structure of the rhinotheca was also observed in wild bird specimens (grey wagtail, king quail, and brown dipper). On the median plane, micro-layers making up the outer and inner layers are bedded nearly parallel to the rostral bone at the base. However, more distally positioned micro-layers of the outer layer are more anteverted distally. The micro-layers of the intermediate layer are bedded nearly perpendicular to those of the outer and inner layers on the median plane. The growth of micro-layers in the intermediate layer adds thickness to the rhinotheca, which causes the difference in profile between the beak bone and the rhinotheca in the distal portion of the beak. Moreover, the entire intermediate layer grows distally as new proximal micro-layers form. The outer layer is dragged distally by the intermediate layer as a result of its distal growth, for the three layers are closely packed to each other at their boundaries. Furthermore, the occurrence of the intermediate and inner layers in the distal portion of the rostral bone may be because the distal end of the beak is frequently used and worn, and the rhinotheca therefore needs to be replaced more frequently at the distal end. The rhinotheca structure described here will be an important and useful factor in the reconstruction of the beaks of birds in extinct taxa.

Effect of two months whole body vibration on hoof growth rate in the horse: A pilot study

Hoof problems are commonly seen in veterinary practice and manipulation of hoof growth rate can be practical and beneficial for that matter. The purpose of this research was to evaluate the effect of whole body vibration (WBV) on hoof growth rate of front feet in the horse. The study was an experimental, single subject, repeated measure design, with all horses serving as control and treatment. Ten horses were subject to WBV, 30 min, twice daily, five days a week, for 60 days in addition to their regular exercise routine. Hoof growth was measured from the reference hairline down to a horizontal groove in both front feet at 30-day (monthly) intervals starting 30 days before the start of treatment (WBV) up until 60 days post cessation of the treatment (WBV). The data analysis was carried out, by applying several paired t-tests to the mean 30-day hoof growth before, during, and after treatment (WBV). A significant mean increase in hoof growth was seen after 30 days WBV (p < 0.001) as well as after 60 days WBV (p = 0.001) with the increase occurring mainly during the first 30 days of WBV. No prolonged effect on hoof growth rate was seen after cessation of WBV. These results indicate that whole body vibration can be used as a non-invasive, safe and non labor-intensive therapeutic modality to accelerate hoof growth in the horse.

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.

Mechanical behavior and quantitative morphology of the equine laminar junction

The horse's hoof is structurally modified for its mechanical functions, but studying the functional design of internal structures is hampered by the external keratinous capsule. Finite-element analysis offers one method for evaluating mechanical function of components within the capsule, such as the laminar junction. This is the epidermodermal connection that binds the hoof wall strongly to the distal phalanx. Primary epidermal laminae (PEL), projecting inward from the wall, vary in morphology and are remodeled despite being keratinous. The aim of this study is to investigate the suggestion that remodeling of PEL is influenced by mechanical stress. Circumferential and proximodistal stress distribution and relative displacement in the laminar junction are assessed by finite-element analysis (FEA) of nine hoof models. Spacing, orientation, and curvature of PEL are assessed from sections through 47 other hooves and compared with the stress and displacement data. Significant correlations are found between laminar spacing and seven displacement and stress variables, supporting the link between stresses and remodeling. Differences in external hoof shape cause regional variation in stress magnitudes around the laminar junction. This finding is in accord with previous observations that laminar morphology is individually regionally variable. This work provides the first concrete link between mechanical behavior and laminar morphology.

Evaluation of architectural changes along the proximal to distal regions of the dorsal laminar interface in the equine hoof

OBJECTIVE

To describe architectural changes along the dorsal laminar interface of the equine foot.

SAMPLE POPULATION

6 macroscopically normal forefeet obtained from 6 equine cadavers.

PROCEDURE

Histologic sections of 8 evenly spaced, proximal to distal, samples of the dorsal laminar interface were photographed, digitized, and examined for differences in architecture. Laminar depth; secondary laminar density; number and consistency of bifurcations occurring within the secondary laminae, and areas composed of primary dermal lamina, primary epidermal lamina, and secondary laminar interface were recorded. Data were examined to test for differences in architecture associated with the proximal to distal positioning of the sample.

RESULTS

With exception of the areas of the primary epidermal and primary dermal lamina, all measured variables were significantly different between the proximal and distal regions of the dorsal laminar interface. Changes included increases in laminar depth and the secondary laminar density. Bifurcation of secondary laminae principally occurred proximally and had an increased depth of bifurcation distally. The secondary laminar dermal-epidermal interface had a 109% increase in area between the most proximal and distal sections.

CONCLUSIONS AND CLINICAL RELEVANCE

Results of this study indicate that the interface normally contributes a substantial volume of dermal components to the internal surface of the wall. These data also indicate that 2 distinct mechanisms (i.e., bifurcation of secondary laminae and an increase in the length of secondary laminae) contribute to changes in the architecture of the laminar interface, which allows for the hypothesis that the normal laminar interface is capable of responding to mechanical load.

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.

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.

Hoof horn abnormalities in Lipizzaner horses and the effect of dietary biotin on macroscopic aspects of hoof horn quality

This study involved a macroscopic evaluation of hoof quality in 152 Lipizzaner horses (130 from Austria and 22 from other countries) and a controlled double blind trial of the effects of biotin on hoof horn growth and quality over 19 months in 42 stallions from the Spanish Riding School (SRS) in Vienna. Using a grading system that incorporated evaluation of horn wall, white line, sole and frog, the macroscopic study revealed the following: 90% of the Austrian Lipizzaners had soft white lines and crumbling, fissured horn at the bearing border of the walls; 39% of the stallions of the SRS, > 4-years-old, had medium to severe hoof horn changes. Daily administration of 20 mg biotin to a test group of horses (n = 26) and a placebo to a control group (n = 16) showed that after 9 months the test group had significantly improved compared to the beginning of the trial and the placebo group (P < 0.01). In the test group, further improvement was observed during the following 5 months and, subsequently, the same good level of hoof condition was maintained over 3 further years of observation. Growth rate of the horn wall was equal in the biotin and placebo group, being 7 mm/28 days, giving a wall renewal period of 11 months. Mean plasma biotin level of untreated horses was 350 ng/l; plasma levels of biotin supplemented horses were > 1000 ng/l. It was concluded that continuous dietary supplementation with biotin at a daily dose of 20 mg is indicated to improve and maintain hoof horn quality in horses with less than optimum quality hoof.