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

Overview

• This study used ultrasound and shear wave elastography (SWE) to measure skin thickness and elasticity in healthy horses.
• It compared these skin properties between horses kept indoors versus those with outdoor access to understand how environment affects skin characteristics.

Objectives

• To noninvasively characterize skin thickness and elasticity in healthy equine subjects using B-mode ultrasonography and SWE.
• To evaluate differences in these skin properties between horses housed exclusively indoors and those with access to outdoor environments.

Methodology

• Subjects: 10 clinically healthy horses were divided into two groups:
  • Indoor group: 5 horses housed exclusively indoors.
  • Outdoor group: 5 horses with temporary or permanent outdoor access.
• Regions Examined: Bilateral skin examination was conducted on three anatomical sites:
  • Neck
  • Withers
  • Girth region caudal to the elbow
• Techniques:
  • B-mode ultrasonography (using 11 MHz linear transducers) measured skin thickness.
  • Shear Wave Elastography (SWE) was used to assess skin elasticity.
• Data Analysis: Comparison of skin thickness and elasticity data between anatomical sites and between the two housing groups.

Findings

• Skin Layer Visualization:
  • Two main cutaneous layers (epidermis and dermis) were identifiable on ultrasound imaging.
  • Dermal sublayers were not distinguishable with current imaging methods.
• Skin Thickness:
  • Small, non-significant differences in thickness were noted between the withers and girth regions compared to the neck; the former two tended to have thicker skin.
  • Horses with outdoor access had significantly thicker skin than those kept indoors, indicating environmental influence on skin morphology.
• Skin Elasticity:
  • SWE measurements showed high variability within the same anatomical regions (coefficients of variation >45%).
  • This variability indicates technical challenges and possibly biological heterogeneity when assessing equine skin elasticity with SWE.

Conclusions and Implications

• Ultrasound and SWE are feasible, noninvasive tools for in vivo assessment of equine skin thickness and elasticity.
• The study provides baseline data on skin characteristics and highlights the significant impact of environmental factors (housing conditions) on skin thickness.
• Technical limitations in SWE variability suggest a need for further refinement of protocols or equipment specific to equine skin assessment.
• These findings may be important for:
  • Clinical dermatological evaluations to better characterize and monitor skin health.
  • Animal welfare monitoring through noninvasive skin condition assessment.
  • Development of species-specific reference standards and diagnostic criteria for skin status in horses.