Would the Cephalic Development in the Purebred Arabian Horse and Its Crosses Indicate a Paedomorphic Process?
Authors: Salamanca-Carreño Arcesio, Parés-Casanova Pere M, Monroy-Ochoa Néstor Ismael, Vélez-Terranova Mauricio
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary: Paedomorphosis in Arabian Horse Head Development Purebred Arabians and their first-generation crosses retain juvenile facial characteristics into adulthood—specifically, a pronounced concave profile—raising questions about whether this represents a developmentally arrested trait. Researchers used geometric morphometrics to analyse 23 anatomical landmarks on lateral head photographs from 99 horses (16 stallions, 53 mares, 30 geldings) ranging from 10 months to 27 years old, reducing variables through principal component analysis to identify consistent profile curvature across age and sex groups. Statistical testing (two-way NPMANOVA and multivariate regression) revealed an isometric relationship between the concave celloid profile observed in juveniles and that present in adults, suggesting the breed genuinely expresses paedomorphosis—a retention of immature morphological traits into skeletal maturity. This finding has implications for understanding breed-specific conformational development and may inform breeding decisions, as the perpetuation of juvenile facial proportions reflects underlying differences in splanchnocranial (facial bone) versus neurocranial (braincase) growth rates. For practitioners involved in breeding, evaluation, or assessing age-related changes in Arabian horses and their crosses, recognising that the refined head profile is a heritable paedomorphic characteristic rather than immaturity itself refines how we interpret normal skeletal maturation in this breed.
Read the full abstract on PubMed
Practical Takeaways
- •The concave head profile characteristic of juvenile Arabian horses is developmentally retained into adulthood as a paedomorphic trait, which is breed-typical and not pathological
- •This morphological pattern appears consistent across sexes and persists in F1 crossbreds, suggesting it may have selective breeding or genetic basis worth considering in breeding decisions
- •Understanding that this cephalic morphology represents normal breed development rather than developmental abnormality may inform equine assessment and selection criteria
Key Findings
- •99 horses (16 stallions, 53 mares, 30 geldings) from purebred Arabian and F1 crossbreds all presented concave celloid lateral left head profiles
- •Geometric morphometrics with 23 landmarks reduced to 14 key landmarks via principal component analysis demonstrated profile curvature differences across sex groups
- •Two-way NPMANOVA and multivariate regression revealed isometric relationship between juvenile and adult head profiles, confirming paedomorphic retention of concave profile into adulthood