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. © 2005 Wiley-Liss, Inc. Key words: finite-element analysis; quantitative morphology;horse; hoof; laminar junction; displacement; stress; biomechanics As a result of being coopted as part of the musculoskeletal system, the equine hoof shares two attributes with that system: numerous modifications for the mechanical functions the hoof performs, and the capacity to respond to variations in loading over time. Hoof anatomy, microstructure, and growth are well documented (Stump, 1967), and ground reaction forces (GRFs) during locomotion have been experimentally recorded to determine the hoof's general mechanical function (Merkens et al., 1993). But the hoof's keratinous capsule and the nature of its attachment to the dermis and skeleton impede detailed study in vivo of its functional design and of the nature and mechanisms of its biological response to variability in loading regimes. Thus, the deceptively simple smooth exterior guards its secrets better than any crenellated castle wall.Finite-element analyses (FEAs) are clearly applicable to this situation, especially given that there are good data on the external shape and loading of the hoof, the properties of its materials and strains in the wall during locomotion. Most previous FEAs of the equine hoof have focused on the capsule (Newlyn et al., 1998;Hinterhofer et al., 2000,

In Standardbreds, mild exercise for 17 weeks caused no significant changes in hoof wall growth or morphometric variables. Subtle changes may develop in equine hooves in response to loading, and mild exercise may not be a strong adaptive stimulus.

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 21 for 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 ¼ 0.039) were found in the controls and in two sagittal measurements of bone length (P ¼ 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.

Understanding the biological responses of hoof tissues to stress should add to the ability to prevent lameness involving the hoof and maintain its health.

Foals’ haematological values change constantly during their first year of life. The use of updated age-based reference intervals (RIs) is imperative for providing accurate diagnosis and optimum care for sick foals. The authors' objective was to provide updated RIs for 13 haematological values in 2, 7, 14, 30, 90, 180 and 365-day-old foals and to investigate the changes over time in each measured value. Venous blood was collected at those ages from clinically healthy foals. Thirteen haematological values were analysed. The 95% RIs were reported using a bootstrapping method. Differences over time were examined using Friedman test. RIs for each of the measured values were calculated. Results showed noticeable trends in changes over time in several values. Nevertheless, white blood cell counts significantly increased between day 2 and day 90 (P=0.011) while lymphocyte counts increased from day 2 up to day 180 (P=0.033). The mean corpuscular haemoglobin and mean corpuscular volume (P=0.011) significantly decreased between day 2 and day 90. Normal haematological values in foals not only differ from those in adult horses but also change throughout the first year of life; thus, it is critical that clinicians use age-based RIs when treating sick foals.