Morphometric Characteristics of the Skull in Horses and Donkeys-A Pilot Study.
Authors: Merkies Katrina, Paraschou George, McGreevy Paul Damien
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary: Skull Morphology in Horses and Donkeys Horses and donkeys, despite sharing the genus Equus, exhibit distinct anatomical differences that influence their management and welfare, yet comparative data on skull structure remain limited. Researchers obtained 14 equine and 16 donkey skulls post-mortem, sectioned them sagittally, and performed detailed morphometric analysis including calculation of skull, cranial and nasal indices alongside measurements of olfactory bulb area (OBA), olfactory bulb pitch angle, and whorl location. Notably, donkeys demonstrated a significantly larger cranial profile than horses, a smaller olfactory bulb area, and a markedly steeper olfactory bulb pitch angle; most striking was the donkey's extremely rostral whorl location compared to the level of the olfactory bulb in horses (p < 0.0001). These structural differences in the nasal cavity and olfactory apparatus may underpin previously documented physiological and behavioural differences between species, with implications for understanding breed-specific sensory capabilities and responses to management practices. For practitioners, these findings support the growing evidence base that horses and donkeys require genuinely differentiated approaches to handling, training and healthcare rather than species-neutral protocols.
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Practical Takeaways
- •Donkeys' distinct skull morphology, particularly their rostral whorl location and smaller olfactory bulb area, may explain differences in sensory perception and behaviour compared to horses—consider these anatomical differences when assessing health, training responses, and welfare needs
- •The steeper olfactory bulb pitch in donkeys suggests different nasal airflow mechanics; this may affect their susceptibility to respiratory conditions and their response to environmental stressors differently than horses
- •Skull morphology differences should inform species-specific management practices, fitting of equipment, and interpretation of clinical signs related to head anatomy
Key Findings
- •Donkeys have a larger cranial profile than horses (p < 0.04) despite no difference in cranial or nasal indices
- •Donkeys have a significantly smaller olfactory bulb area (OBA) and steeper olfactory bulb pitch compared to horses (p < 0.05 and p < 0.02 respectively)
- •Whorl location differs markedly between species: corresponding to olfactory bulb level in horses but extremely rostral in donkeys (p < 0.0001)
- •Clear differentiation in skull morphology exists between horses and donkeys that may underlie physiological and behavioural differences