Hair coat properties of donkeys, mules and horses in a temperate climate.
Authors: Osthaus B, Proops L, Long S, Bell N, Hayday K, Burden F
Journal: Equine veterinary journal
Summary
# Hair Coat Adaptation in Equids: Implications for Donkey Welfare in Temperate Climates Donkeys evolved in arid regions and retain physiological traits poorly suited to cold, wet climates, yet are frequently kept in temperate zones without adequate environmental protection. Osthaus and colleagues conducted a longitudinal study measuring hair weight, length and diameter from 18 donkeys, 16 horses and eight mules across all four seasons to evaluate whether these species show differential thermoregulatory adaptation. Donkeys failed to develop a meaningful winter coat—their hair remained consistently light, short and thin year-round, whereas horses and mules both demonstrated substantial seasonal thickening by December. These findings suggest that donkeys cannot rely on natural pelage insulation when exposed to UK winter conditions, creating a genuine welfare concern for animals kept at pasture without shelter. For practitioners, the practical implication is clear: donkeys maintained outdoors in temperate climates require mandatory access to weatherproof shelter (wind and waterproof) rather than the open field conditions that suffice for horses, and individuals working with donkeys should factor this into grazing management, stable design and animal assessment protocols.
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Practical Takeaways
- •Donkeys require wind and waterproof shelter access year-round in temperate climates, as they cannot grow adequate winter coats for natural cold protection
- •Mules have better cold adaptation than donkeys but less than horses; assess individual shelter needs accordingly
- •Winter coat absence in donkeys is a physiological limitation, not a management oversight—environmental protection is essential for welfare
Key Findings
- •Donkeys' hair coats do not significantly change across seasons, unlike horses which grow thicker winter coats
- •Donkey hair was significantly lighter, shorter, and thinner than horses and mules in winter months
- •Mules showed intermediate seasonal coat changes between donkeys and horses
- •Donkeys and mules appear less physiologically adapted to cold, wet climates than horses