Ultrasonography and shear wave elastography of equine skin: a preliminary study

To noninvasively characterize skin thickness and elasticity in healthy horses using B-mode ultrasound and shear wave elastography (SWE) and to verify whether there are differences between the skin of stabled and outdoor horses.

10 clinically healthy horses were enrolled in this study. Five animals were housed exclusively indoors (indoor group), and 5 had temporary or permanent access to an outdoor environment (outdoor group). All horses underwent bilateral ultrasonographic examination of 3 anatomical regions: neck, withers, and girth region caudal to the elbow. Skin thickness was assessed using B-mode ultrasonography, and SWE was employed to evaluate tissue elasticity. Both modalities were performed using linear transducers at 11 MHz. Data were compared between regions and between groups.

2 cutaneous layers, the epidermis and dermis, were distinguishable, although dermal sublayers could not be identified. Mean skin thickness was slightly greater (not significant) at the withers and girth regions compared to the neck. Horses with outdoor access exhibited significantly thicker skin than those housed indoors. Shear wave elastography measurements demonstrated high intraregional variability, with coefficients of variation exceeding 45%, highlighting technical challenges in assessing equine skin elasticity.

This study confirms the feasibility of ultrasound and SWE for in vivo evaluation of equine skin, providing foundational data and emphasizing the influence of housing conditions on skin characteristics.

The findings of this study may have implications for clinical dermatological evaluations, welfare monitoring, and the development of species-specific reference values for skin assessment.