Danae Tapia

The Patagonian huemul (Hippocamelus bisulcus) and the Southern pudu (Pudu puda) are native South American cervids that differ in body size, ecology, and conservation status. However, quantitative evidence linking vertebral trabecular microarchitecture with biomechanical behavior in these species remains scarce. This study aimed to comparatively characterize vertebral trabecular bone structure and its mechanical response using an integrative, non-destructive approach. Vertebral bodies from cervical, thoracic, and lumbar regions were analyzed using high-resolution micro-computed tomography to quantify structural parameters, followed by finite element analysis to estimate deformation and von Mises stress under standardized axial compression. Both specimens exhibited consistent regional variation, with cervical vertebrae showing lower density and organization, and thoracic–lumbar vertebrae displaying denser trabecular networks. The Southern pudu specimen appeared to present a more homogeneous microarchitecture and a relatively uniform mechanical response along the vertebral column. In contrast, the Patagonian huemul specimen tended to show greater structural heterogeneity, with apparently higher deformation and stress values, particularly in the cervical region. These findings suggest that trabecular organization may contribute to the differences in vertebral mechanical behavior observed between the analyzed specimens. This study provides a preliminary comparative baseline for understanding skeletal adaptation and structural vulnerability in South American cervid species. This exploratory analysis is based on single specimens per species and should be interpreted as preliminary evidence rather than population-level inference.

The Patagonian huemul ( Hippocamelus bisulcus ), a critically endangered South American cervid, has undergone a severe population decline, and extant populations exhibit a high prevalence of skeletal disorders associated with chronic mineral deficiencies. Despite the biomechanical, postural, and clinical relevance of the axial skeleton, detailed information on its external morphology, internal architecture, morphometry, and elemental composition remains scarce for this species. Here, we address this gap by providing an integrative, multiscale characterisation of the postcranial axial skeleton of the Patagonian huemul. We hypothesised that the axial skeleton exhibits consistent regional patterns in external morphology, internal microarchitecture, and elemental composition identifiable using non‐destructive analytical approaches. Three complete axial skeletons were examined using macroscopic anatomical analysis and linear morphometry, helical computed tomography with three‐dimensional reconstruction, and semiquantitative energy‐dispersive X‐ray spectroscopy. Cervical, thoracic, lumbar, and sacral vertebrae, as well as ribs and sternum, were analysed following standardised veterinary anatomical terminology. CT imaging revealed regionally organised distributions of cortical and trabecular bone, including consistent basivertebral foramina and elongated internal cavities, together with segment‐specific variations in internal density. Elemental analysis of compact bone demonstrated variable proportions of principal constituents among axial regions, with lumbar vertebrae showing the highest relative mineral content. These findings establish a comprehensive anatomical reference framework for the axial skeleton of the Patagonian huemul, complementing previous descriptions of the appendicular skeleton and cranial structures.

Navicular syndrome (NS) is a chronic, degenerative condition of the equine thoracic limb that compromises the distal sesamoid bone (DSB) and associated structures responsible for stabilization and load absorption during locomotion. Although historically attributed to vascular alterations, its etiology is now recognized as biomechanical, characterized by chronic overload of the deep digital flexor tendon. Conventional diagnostic techniques—radiography, scintigraphy, and ultrasonography—lack the sensitivity and precision required to detect early microarchitectural alterations. This study aimed to evaluate changes in the trabecular microarchitecture of the DSB in horses with and without NS using micro‐computed tomography (micro‐CT) and to explore its diagnostic potential. Samples from eight horses (NS group, n = 4; Not affected group (control), n = 4) were analyzed. Micro‐CT images were processed to obtain parameters such as bone volume, relative density, trabecular thickness and separation, porosity, and connectivity. Group comparisons were performed using nonparametric tests and Pearson correlation analyses to explore internal structural relationships. Correlations between groups were then compared using Fisher's Z test. Horses with NS exhibited lower bone volume, trabecular density, thickness, and connectivity, alongside increased trabecular separation, porosity, and anisotropy compared to controls. In healthy horses, strong positive correlations between volume and density, and inverse relationships with trabecular fragmentation, indicated an elevated, well‐connected architecture. By contrast, affected horses displayed deteriorated microarchitecture with compensatory trabecular consolidation, reduced trabecular numbers, and a more cylindrical structure—signifying pathological adaptation. Two correlations differed significantly between groups, underscoring disease‐induced microstructural reorganization. Micro‐CT effectively identified navicular syndrome–specific microarchitectural changes not detectable with conventional methods, yielding quantifiable metrics (thickness, separation, and porosity) that may serve as early diagnostic and monitoring biomarkers. These findings justify broader studies with larger sample sizes and longitudinal designs to validate clinical applicability.