Application of 3D scanning for modeling and morphometric assessment of Mangalarga Marchador horses

Morphometric traits are essential for assessing conformation, locomotion, and selection in equine breeding programs. However, manual measurements are laborious, require physical contact, and may cause stress to animals, highlighting the need for alternative technologies.

This study evaluated the use of a portable 3D scanner for three-dimensional modeling and morphometric assessment of Mangalarga Marchador horses.

Fifty-two adult horses were measured using manual and 3D scanning methods to assess ten morphometric traits: withers height (WH), hip height (HH), head length (HL), neck length (NL), back-loin length (BLL), croup length (CL), shoulder length (SL), body length (BL), head width (HW), and croup width (CW). Descriptive analyses summarized the distribution of 3D model quality by coat color and body region. Associations between methods were evaluated using Pearson correlation, while agreement was assessed using Bland-Altman analysis and the intraclass correlation coefficient (ICC).

The torso showed the highest proportion of satisfactory 3D reconstructions, whereas lower quality models were mainly observed in the limbs, head, and neck. Model quality was similar between coat colors. Higher correlations between manual and 3D measurements were observed for withers height, hip height, shoulder length, body length, and croup width (r > 0.60), with moderate to good agreement (ICC: 0.697-0.784; LoA:9.94 - 5.20 cm). Traits related to the head, neck, and back-loin showed lower correlations and agreement (ICC < 0.30).

Portable 3D scanning generated accurate models and reliable morphometric measurements for major body dimensions, although agreement was lower for more mobile anatomical regions.