The evaluation of conformation traits is an important part of selection for breeding stallions
and mares. Some of these judged conformation traits involve joint angles that are associated with
performance, health, and longevity. To improve our understanding of the genetic background
of joint angles in horses, we have objectively measured the angles of the poll, elbow, carpal,
fetlock (front and hind), hip, stifle, and hock joints based on one photograph of each of the
300 Franches-Montagnes (FM) and 224 Lipizzan (LIP) horses. After quality control, genome-wide
association studies (GWASs) for these traits were performed on 495 horses, using 374,070 genome-wide
single nucleotide polymorphisms (SNPs) in a mixed-eect model. We identified two significant
quantitative trait loci (QTL) for the poll angle on ECA28 (p = 1.36 x 10E-07), 50 kb downstream of the
ALX1 gene, involved in cranial morphology, and for the elbow joint on ECA29 (p = 1.69 x 10E-07), 49 kb
downstream of the RSU1 gene, and 75 kb upstream of the PTER gene. Both genes are associated
with bone mineral density in humans. Furthermore, we identified other suggestive QTL associated
with the stifle joint on ECA8 (p = 3.10 x 10E-07); the poll on ECA1 (p = 6.83 x 10E-07); the fetlock joint
of the hind limb on ECA27 (p = 5.42 x 10E-07); and the carpal joint angle on ECA3 (p = 6.24 x 10E-07),
ECA4 (p = 6.07 x 10E-07), and ECA7 (p = 8.83 x 10E-07). The application of angular measurements in
genetic studies may increase our understanding of the underlying genetic eects of important traits
in equine breeding.