Genetic relationship between Neck and Limb defects in Pura Raza Española Horses.

Background: : Defects affecting the horse’s neck and limb conformation can negatively impact a horse’s performance and suitability for equestrian activities. Objectives: : to assess the prevalence of the simultaneous occurrence of defects in the limbs and neck and to estimate the genetic correlations between these defects Study design: Retrospective cohort study. Methods: : Prevalence and genetic correlations between 12 conformational limb defects and 2 neck defects were analyzed in 56644 Pura Raza Española horses. Different approaches were used: A) two-class for neck and limb defects (0-no defect, 1-presence of defect); B) three-class for limb defects (0-no defect, 1-slight defect, 2-serious defect) and four-class for neck defects (0-no defect, 1-slight defect, 2-serious defect, 3-disqualifying defect). Genetic correlations between conformational defects were estimated using a multivariate animal model within a Bayesian framework with the BLUPF90 software family, including age as a covariate, and gender, coat color, management of breeder’s stud farm and inbreeding as fixed effects Results: : The most prevalent limb defect in horses affected with Cresty neck (CN) and Ewe neck (EN) was Splay-footed rear limb (SFR) (80.2% and 72.5%, respectively). The genetic correlations ranged from -0.22 + 0.090 for EN- SFR to 0.44 + 0.123 for CN-Divergent hock, and in approach B, -0.25 + 0.028 for CN-Convergent hock to 0.51 + 0.228 for CN- Splay-footed forelimb Main limitations : The veterinarians responsible for evaluating the horses are unknown. Data were only collected once during the animal’s lifetime, making it impossible to determine how the defects evolved over time. Conclusions: : This study revealed a moderate relationship between limb and neck defects, emphasizing the need for meticulous planning to improve these defects in the PRE breed.