Excessive biomechanical stresses are commonly believed to be important in the pathogenesis of various osteoarticular disorders. In order to explain better the relation between equine digital morphometric parameters and biomechanical stresses, a sensitivity analysis has been performed to compare individual effect of each equine digital morphometric parameter on kinetics.

In locomotor biomechanics, three high groups of contraints are commonly encountared: pressure, traction and torsion. In supramaximal conditions, all of these contraints would be responsible of some equine diseased locomotor systems. In order to understand better the contraints in the equine locomotor dynamics, some investigations have been carried out. Moreover, some measurement methods, based on the mechanics of Newton, have been performed. This review shows the different measurement techniques and introduces the mechanical basis that are compulsory for the understanding of the equine locomotor apparatus functioning.

An equine fetlock joint pendulum test was studied and the influence of post mortem time and intra-articular lipid solvent on the viscous frictional response examined. Fresh equine digits (group 1, n=6 controls; group 2, n=6 lipid solvent) were mounted on a pendulum tribometer. Assuming that pendular joint damping could be modelled by a harmonic oscillator fluid damping (HOFD), damping time (τ), viscous damping coefficient (c) and friction coefficient (μ) were monitored for 5h under experimental conditions (400N; 20°C). In all experiments, pendular joint damping was found to follow an exponential decay function (R(2)=0.99714), which confirmed that joint damping was fluid. The evolution of τ, c and μ was found to be significantly (P<0.05) different in the two groups, with a decrease in τ and an increase in c and μ that was faster and more prominent in digits from group 2. It was concluded that pendular joint damping could be modelled by a HOFD model. The influence of post mortem time on results suggested that, ideally, joint mechanical properties should only be tested on fresh cadavers at the same post mortem time. Moreover, the addition of lipid solvent was found to be responsible for upper viscous friction parameters and for a reduced damping time, which suggested that articular lubricating ability was compromised. This equine pendulum test could be used to test the efficacy of various bio-lubricant treatments.

Introduction: To calculate flexor tendon forces on the basis of inverse dynamic analysis, flexor tendon moment arms need to be determinated in the equine distal forelimb. Moment arm of deep digital flexor tendon (dDDF) and of superficial digital flexor tendon (dSDF) have been recognised to vary during the fetlock joint dorsiflexion, however little distal forelimb model has taken into account dSDF and dDDF variations. This study describes a method to determinate the relationship between the fetlock joint dorsiflexion and the flexor moment arms variations. Methods: Eleven forelimbs of eleven horses (~500 Kg) were collected, transversally cut below the shoulder joint, frozen and cut into a sagittal plane until above the fetlock joint. Considering the forelimb pulley model (Meershoek et al. AJVR 2001; 62 1585-1593), in the segment based coordinate system, for the fetlock joint the pulley centers of the DDF and SDF tendons were determined directly from the section. For the fetlock radius-pulley experiments, forelimbs were thawed overnight, fixed to an immobilizing support and attached to a hoist that dorsiflexed the fetlock joint. For the fetlock dorsal angle (θ) 180° to 150°, the dDDF and the dSDF were measured directly from the section. For each tendon all of these data were fitted using a polynomial regression model (OriginPro8) and the relationships between θ and the radius pulley variation (Δd) was described assuming that Δd was zero at θ equal to 180°. Results : When the fetlock dorsiflexion increased, dDDF and dSDF decreased (ΔdDDF(150)= -6.1 mm; ΔdSDF(150)= -5.2 mm) according to the following equations: ΔdDDF(θ)= -0.24923 x θ1 + 0.00139 x θ² (R²=0.89867) ; ΔdSDF(θ)= -0.21494 x θ1 + 0.0012 x θ² (R²=0.91504). Conclusions : A distal forelimb pulley model with variable dDDF and dSDF has been performed. It could become an important tool for use in inverse dynamic procedures.

THE SYNOVIAL JOINT : A PERFECT TRIBOLOGICAL SYSTEM The synovial joint, by load bearing and by minimal wear and minimal friction conferring, is considered as a perfect tribological system. During these last years, researchs in articular biomechanics have been performed to study how the joint friction coefficient, a dimensionless measure which represents the ratio between the frictional force on the normal force, was close to zero. Today, there is still no consensual explanation and the articular prosthesis partially imitates the biological mechanics. This review describes the composition and the general properties of the synovial joint components. Additionally, different theorical models, on the tribology of the articular triplex cartilage-synovial fluid-cartilage, are explained. AKIZUKI S., MOW V.C., MULLER F., PITA J.C., hOWELL D.S. Tensile properties of human knee joint cartilage. II. Correlations between weight bearing and tissue pathology and the kinetics of swelling. J. Orthop. Res., 1987, 5, 173-186. AKIZUKI S., MOW V.C., MULLER F., PITA J.C., hOWELL D.S., MANICOURT D.h. Tensile properties of human knee joint cartilage: I. Influence of ionic conditions, weight bearing, and fibrillation on the tensile modulus. J. Orthop. Res., 1986, 4, 379392. ALMOND A., ShEEhAN J.K., BRASS A. Molecular dynamics simulations of the two disaccharides of hyaluronan in aqueous solution. Glycobiology, 1997, 7, 597-604. ALWAN W.h., CARTER S.D., BENNETT D., EDWARDS g.B. glycosaminoglycans in horses with osteoarthritis. Equine Vet. J., 1991, 23, 44-47. ALWAN W.h., CARTER S.D., BENNETT D., MAy S.A., EDWARDS g.B. Cartilage breakdown in equine osteoarthritis: measurement of keratan sulphate by an ELISA system. Res. Vet. Sci., 1990, 49, 56-60. ANADERE I., ChMIEL h., LASChNER W. Viscoelasticity of «normal» and pathological synovial fluid. Biorheology, 1979, 16, 179-184. ANgLIN T.C., COOPER M.P., LI h., ChANDLER K., CONBOy J.C. Free energy and entropy of activation for phospholipid flip-flop in planar supported lipid bilayers. J. Phys. Chem. B, 2010, 114, 19031914. ASPDEN R.M., hUKINS D.W. Collagen organization in articular cartilage, determined by X-ray diffraction, and its relationship to tissue function. Proc. R. Soc. Lond. B Biol. Sci., 1981, 212, 299-304. ATEShIAN g.A. A theoretical formulation for boundary friction in articular cartilage. J. Biomech. Eng., 1997, 119, 81-86. ATEShIAN g.A. The role of interstitial fluid pressurization in articular cartilage lubrication. J. Biomech., 2009, 42, 1163-1176. AUgER D.D., DOWSON D., FIShER J., JIN Z.M. Friction and lubrication in cushion form bearings for artificial hip joints. Proc. Inst. Mech. Eng. H, 1993, 207, 25-33. AVIAD A.D., hOUPT J.B. The molecular weight of therapeutic hyaluronan (sodium hyaluronate): how significant is it? J. Rheumatol., 1994, 21, 297-301. BAhABRI S.A., SUWAIRI W.M., LAXER R.M., POLINKOVSKy A., DALAAN A.A., WARMAN M.L. The camptodactyly-arthropathy-coxa vara-pericarditis syndrome: clinical features and genetic mapping to human chromosome 1. Arthritis Rheum., 1998, 41, 730-735. BAO J.P., ChEN W.P., WU L.D. Lubricin: a novel potential biotherapeutic approaches for the treatment of osteoarthritis. Mol. Biol. Rep., 2010. BARONE R. Caracteres generaux des articulations. In : Barone R., Anatomie comparee des mam- BIBLIOGRAPHIE

THE SYNOVIAL JOINT : A PERFECT TRIBOLOGICAL SYSTEMThe synovial joint, by load bearing and by minimal wear and minimal friction conferring, is considered as a perfect tribological system. During these last years, researchs in articular bio-mechanics have been performed to study how the joint friction coefficient, a dimensionless measure which represents the ratio between the frictional force on the normal force, was close to zero. Today, there is still no consensual explanation and the articular prosthesis partially imitates the biological mechanics.This review describes the composition and the general properties of the synovial joint components. Additionally, different theorical models, on the tribology of the articular triplex cartilage-synovial fluid-cartilage, are explained.

This study describes an equine joint friction test using a cartilage-on-cartilage arrangement and investigates the influence of age and load on the frictional response. Osteochondral plugs were extracted from equine shoulder joints (2-5 years, n=12; 10-14 years, n=15), and mounted in a pin-on-disc tribometer. The frictional response was then measured under constant conditions (2N; 20 degrees C; 5 mm/s), and with increasing load (2N, 5N, 10N). In all experiments, the friction coefficient of young cartilage was significantly (P<0.001) smaller than obtained from old cartilage, while the application of a greater load resulted in a significant (P<0.001) decrease in friction coefficient only in old cartilage. It was concluded that cartilage ageing was responsible for an increase in friction coefficient under these experimental conditions. Moreover, where young cartilage lubrication remained stable, cartilage ageing may have been responsible for lubrication regime change. The cartilage-on-cartilage model could be used to better understand lubrication regime disturbances in healthy and diseased equine joints, and to test the efficacy of various bio-lubricant treatments.

Introduction: This website is a multi-dimensional approach of the locomotor system in domestic animals. The first objective of this anatomical presentation is to establish relation between systemic anatomy and topographic anatomy. The second objective is to teach a practical anatomy that must be adapted to the clinician work. Methods: From the dissection of equine, bovine and canine specimens, osteology, arthrology and myology (OAM) were photographed and filmed. All photos and movies were captioned and designed using Fireworks (Adobe CS4, USA), AVS video converter 6 (MediaTechnologies Ltd, UK) and Divx Author (Divx Inc, USA). The website was designed using Dreamweaver (Adobe CS4, USA). Results: Compared anatomy site consists on dichotomously organised web pages. Each page is transversally and vertically connected with others, and always surmounted by a navigation barr. From the navigation barr we can travel through different drop-down menus (DDM). The first DDM corresponds to the lesson menu (it sends to general OAM); the second and third DDMs correspond to the equine picture menu and the bovine/canine picture menu (from them we can navigate in OAM per species and per system using clickable captioned photos and movies, the functional aspects being explained). For practical reasons, equine species is used as animal reference. Indeed only anatomical differences of the other species are detailed and compared. Finally the button Index corresponds to the surgeon view (all of the body is transversally cut, the clickable anatomical structures are sent back to their specific topic web page). Conclusions: Because of the numerous photos and movies, the three-dimensional view is better understood. Because of the transversal and vertical links, the navigation, in whatever level per species or per system or per anatomical cut, strengthens the cognitive process. This web site is a fabulous multi-scale tool to teach and to learn the veterinary anatomy.

REASONS FOR PERFORMING STUDY Whereas the effect of heel configuration on the tension of the suspensory apparatus is well documented in the literature, there are few reports of joint contact force components in the equine distal forelimb. OBJECTIVES To improve understanding of the effect of heel configuration on equine digit joint loading, a sensitivity analysis was performed to compare the effect of a raised heel on joint contact force components in the coffin and fetlock joints during the stance phase of the trot. MATERIALS AND METHODS Four Warmblood horses were used. An inverse dynamic analysis was carried out using kinematic and kinetic data. Taking into account the tendon wrapping forces (WF) around the sesamoid bones in the calculations, the joint contact forces (CF) were estimated for the coffin and fetlock joints during the trot stance phase (4 m/s). To test the sensitivity of the results to heel configuration changes, calculations were performed repeatedly for different heel configurations (raised by 0, 6 and 12°). A one-way ANOVA with repeated measures was used to test the effect of heel configuration (at the 3 levels) (α = 0.05; P < 0.05; post hoc testing: Bonferroni). RESULTS For heel configurations raised from 0-12°: whereas the tension of the deep digital flexor tendon decreased and the tension of the superficial digital flexor tendon increased, for the coffin joint the peak WF (1.4 ± 0.25 bwt; 1.2 ± 0.2 bwt; 0.95 ± 0.1 bwt) and the peak CF (2.45 ± 0.25 bwt; 2.2 ± 0.2 bwt; 2 ± 0.1 bwt) decreased significantly (P < 0.05). For the fetlock joint, the peak WF (3.8 ± 0.7 bwt; 4.1 ± 0.3 bwt; 4.4 ± 0.25 bwt) and the peak CF (4.35 ± 0.7 bwt; 4.7 ± 0.35 bwt; 5 ± 0.3 bwt) increased, but not significantly. CONCLUSION This analysis suggests that the coffin joint loading and fetlock joint loading are strongly connected. The heel configuration may influence both coffin joint and fetlock joint contact force components.

Introduction: In order to explain better the correlation between mechanical loading and osteoarticular disorders, joint contact forces and internal bone forces were recently investigated in human biomechanical studies. Little research has yet been done on this subject in the horse, indeed this study describes a procedure estimating joint contact force in the equine digit during the stance phase of a trot simulation (4 m/s).

Les connaissances relatives aux cervides sont de plus en plus etendues. La presente synthese vise a rapporter a partir des donnees recentes de la litterature les caracteristiques essentielles de la reproduction des principales especes : anatomie de l'appareil reproducteur, duree de la saison de reproduction, differents parametres du cycle sexuel, endocrinologie du cycle sexuel et de la gestation. Il vise egalement a mettre en evidence les particularites differenciant les cervides des ruminants domestiques, telle par exemple la diapause embryonnaire rencontree chez le chevreuil.

Knowledge about cervids are rapidly growing. This work aims to present the more recent scientific information on reproductive physiology and endocrinology of the cervids: anatomy of the genital tract, length of breeding season, parameters and endocrinology of the reproductive cycle, endocrinology of pregnancy. It also aims to highlight differences between cervids and domestic ruminants such as embryonic diapause observed in Capreolus capreolus.

Navicular bones from the four limbs of 95 horses, classified in 9 categories, were studied. The effects of age on navicular bone morphometry and histomorphometry were estimated, after adjustment of the data to even out the effects of front and rear limbs, morphometrical type, sex, weight, and size.

The scoring system based on the different types of navicular distal border canals is a good method to quantify and relativise the anomalies in number, shape and localisation of the canals. The distal border score varies significantly with the limb (fore or rear), the morphological type, the gender and the age of the horse. These anatomical variations are of importance and must be taken into account when examining a suspect bone. The score is larger for the fore navicular bone than for the rear. It could be interesting to compare both scores: rear navicular bone score is generally equal to half (or slight less) that of the fore. The score is larger for heavy types of horses and ponies (drafthorse, heavy halfbreds and Fjords). This phenomenon could be related to a larger pressure within the distal interphalangeal joint. The score is lower for the athletic half bred than for other halfbreds. This could be the result of the changes in bone architecture induced by exercise and particularly bone densification. The score is lower for the female than for the male. We think that navicular bone quality is better for the female and this idea corroborates that of other authors that consider that the risk to develop navicular disease is smaller for the female than for the male. The score increases with age. it is particularly small in young horses less than two years old and then increases strongly. This phenomenon is to be related to the progressive development, in the first year of life, of the groove between articular cartilage and distal impar ligament, canals developping only later one. In athletic horses, the score is higher between 7 and 12 years of age. During this time, we also observe more degenerative changes within the navicular bone, which could mean that bone is of lesser quality.