Malunion of an In Utero Metacarpal Fracture in a Standardbred Mare Presenting for Dystocia.
Authors: Lection Jennine, Delvescovo Barbara, Percival Aaron, Wu Timothy, Southard Teresa, Diel de Amorim Mariana, Cheong Soon Hon
Journal: Journal of equine veterinary science
Summary
# Editorial Summary In utero fractures of long bones represent an uncommon equine condition, with most affected foals typically being lost to abortion; however, this case documents a rare presentation of a term foal with malunion of a metacarpal fracture that contributed directly to dystocia in a 7-year-old Standardbred mare. The dystocia proved refractory to both assisted and controlled vaginal delivery techniques because the foal's contracted tendons prevented normal limb flexion and extension, ultimately necessitating emergency caesarean section. Computed tomography imaging, gross examination, and histological assessment of the foal's right metacarpus confirmed previous fracture with subsequent malunion—a skeletal defect that had developed entirely in utero. Whilst isolated cases of in utero fractures have been reported in the literature, almost all previous documentation involved aborted foetuses rather than term foals, making this case particularly significant as it establishes congenital skeletal malunion as a potential and previously unrecognised cause of dystocia. Practitioners managing dystocia cases characterised by mechanical obstruction and apparent muscular rigidity should consider the possibility of underlying congenital skeletal or tendon abnormalities, particularly when standard obstetric manoeuvres prove unsuccessful.
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Practical Takeaways
- •Include in utero fractures with malunion in the differential diagnosis for mares presenting with dystocia, particularly when mechanical obstruction is suspected.
- •Advanced imaging (CT) combined with post-mortem examination should be performed on foals with congenital contractures or flexural deformities to identify underlying in utero fractures.
- •Recognition of in utero fractures as a potential cause of dystocia may alter management decisions regarding assisted delivery versus cesarean section.
Key Findings
- •Malunion of an in utero metacarpal fracture was identified in a full-term foal presented for dystocia, a previously unreported presentation.
- •Contracted tendons secondary to the metacarpal malunion impeded fetal flexion and contributed to dystocia requiring cesarean section.
- •Computed tomography combined with gross and histologic examination confirmed the in utero fracture and subsequent malunion in the right metacarpus.
- •This case represents a novel etiology for dystocia in mares and expands the differential diagnosis for congenital musculoskeletal abnormalities in term foals.