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The repair process of tendon injuries, which are common in both human and equine athletes, is slow and the quality of the repair tissue is often inferior to the original tendon tissue, which frequently leads to re-injury. The relatively poor vascularization of tendons is considered to be one of the reasons for their limited healing potential. Recently, platelet-rich plasma (PRP), an autologous concentrate of platelets, rich in growth factors, has been shown to enhance the repair process of injured tendons. This effect has been ascribed to the high levels of growth factors in PRP, several of which are known to be involved in tendon repair. Among many other growth factors, the vascular endothelial growth factor, a powerful stimulator of angiogenesis, is abundantly present in PRP, suggesting that enhancement of neovascularization might be one of the working mechanisms. In this study, the effect of PRP on neovascularization was studied in experimentally induced tendon injuries using color Doppler ultrasonography and immunological staining of Factor VIII. PRP induced significantly more neovascularization than the placebo treatment until at least 23 weeks after treatment, as detected by both Doppler ultrasonography and Factor VIII staining. Neovascularization might be one of the explanations for the long-lasting effect of a single intratendinous treatment with PRP.

Summary Reasons for performing study: There is little insight into the effects of routine farriery on the internal structures of the distal limb in sound horses. Objectives: To measure the effect of change in hoof conformation during a shoeing interval on the moments about the proximal and distal interphalangeal joints (PIPJ, DIPJ) and to determine whether and how the horse compensates for this change in hoof conformation. Methods: Both front feet of 9 sound Warmblood horses were measured while standing on a pressure‐force measuring system and radiographed in a lateromedial direction shortly after shoeing and 8 weeks later. From these data, ground reaction forces (GRF) and lever arms were measured in order to calculate joint moments. Results: After 8 weeks, the moment about the PIPJ did not increase significantly, but the moment about the DIPJ did so, indicating a compensatory mechanism for a change in hoof conformation in the DIPJ. Conclusions: Standing horses compensate for hoof conformation change during an 8‐week shoeing interval, which leads to increased DIPJ extension and consequently an increased loading of the deep digital flexor tendon. Potential relevance: This study quantifies the effect of a shoeing interval on the internal structures of the foot and helps to determine an appropriate shoeing interval for individual horses in which the hoof with the lowest hoof angle is the best indicator. The exact determination of an optimal individual shoeing interval requires further study.

Summary Reasons for performing study: In order to optimise shoeing and shoeing conditions, it is essential to know how the horse adapts to a common shoeing interval. Objectives: To measure changes in location of the centre of pressure (CoP) and hoof‐unrollment pattern during a shoeing interval and to assess whether these changes in CoP result directly from changes in hoof conformation or are also influenced by compensatory mechanisms. Methods: Eighteen horses were trotted over a pressure‐force measurement system shortly after shoeing and 8 weeks later. The position of the CoP was measured and also predicted using calculations based on changes in hoof conformation. Results: The measured shift in CoP was less than calculated. This difference was largest in the hind feet. The hoof‐unrollment pattern stayed basically the same in the front feet, but in the hind feet there was a substantial lateral shift of the trajectory of the CoP. Conclusions: Horses can compensate, to a certain extent, for changes in hoof conformation that develop during 8 weeks on shoes. As the capacity to compensate is less in the forelimbs, the relative increase in loading of these limbs during a shoeing interval is larger than in the hindlimbs. Potential relevance: This study provides essential basic data for the development of science‐based shoeing techniques.

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