Radiographic Appearance of the Fore Digit and Carpal Joint in the Mule Foal from Birth to 3 Months of Age.
Authors: Nocera Irene, Sorvillo Benedetta, Sgorbini Micaela, Aliboni Benedetta, Citi Simonetta
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Radiographic development in mule foals has never been systematically documented, despite the species' growing popularity in equestrian work. Researchers radiographed the forelimbs of five healthy mule foals (ten limbs total) weekly through their first month of life, then bi-monthly to three months, tracking growth plate closure timing, skeletal morphology, and carpal bone mineralisation. Growth plate closure occurred sequentially and in a protracted pattern: the middle phalanx distal growth plate was already closed at birth, whilst the proximal plate began closing around two months; the first phalanx distal plate closed by day seven but the proximal plate not until three months; and the third metacarpal distal plate initiated closure at two months. Notably, the distal phalanx transitioned from a triangular shape at birth to developing palmar processes by one month, with sesamoid bones achieving their final trapezoidal form by three months, whilst the hoof capsule underwent progressive thickening without evidence of distal phalangeal remodeling within it. These findings establish a crucial radiographic baseline for practitioners managing mule foals, revealing that skeletal development patterns fall intermediate to those documented in horses and donkeys—a distinction that carries clear implications for assessing normality, timing intervention for developmental disorders, and potentially adjusting early management protocols specific to mules rather than applying equine standards directly.
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Practical Takeaways
- •Farriers and veterinarians now have a reference timeline for normal growth plate closure in mule foals, allowing earlier detection of developmental abnormalities in this understudied species
- •The intermediate radiographic features of mules between horses and donkeys suggest that equine growth standards cannot be directly applied to mules—species-specific assessment criteria are necessary
- •Hoof capsule thickness increases proportionally with digit growth during the first 3 months; monitor hoof development carefully as foals transition through this critical growth period
Key Findings
- •Middle phalanx distal growth plate closed at birth; proximal physis closure began around 2 months; first phalanx distal physis closed by 7 days with proximal closure starting at 3 months
- •Third metacarpal distal physis began closing at 2 months of age in mule foals
- •Carpal bones were immature at birth and progressed toward maturity over the 3-month observation period
- •Distal phalanx morphology evolved from triangular at birth to development of palmar processes by 1 month and trapezoidal sesamoid bones by 3 months
- •Mule foal radiographic features were intermediate between those of horses and donkeys, establishing baseline normal parameters for interpretation