Rib fracture as a cause of hindlimb lameness in a horse
Authors: Jimenez‐Rihuete Pablo, Staempfli Simon A., Waterhouse Mathew, Rubio‐Martínez Luis M.
Journal: Equine Veterinary Education
Summary
# Editorial Summary A 2-year-old Thoroughbred racing gelding presented with moderate right hindlimb lameness (6/10) that failed to respond to conventional regional anaesthesia of the affected limb, prompting investigation of alternative pain sources. Gamma scintigraphy identified a focal area of severe radiopharmaceutical uptake over the dorsal aspect of the right 18th rib, with ultrasonography subsequently confirming a complete, displaced fracture of the proximal rib; crucially, local anaesthetic infiltration around the fracture site (10 mL cranially and caudally) completely resolved the hindlimb lameness, establishing the rib fracture as the primary pain generator. The neuroanatomical mechanism likely involves referred pain or direct irritation along the thoracolumbar fascia and associated musculature, structures that share innervation with the hindlimb region. Following 12 weeks of box rest, the horse returned to ridden exercise and achieved soundness at 12-month follow-up, suggesting favourable healing despite the proximal rib location. For practitioners, this case underscores the importance of considering caudal rib fractures in differential diagnoses for hindlimb lameness unresponsive to standard regional blocks, and demonstrates that diagnostic local anaesthesia applied directly to suspected rib fractures can definitively confirm musculoskeletal pain sources beyond the limb itself.
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Practical Takeaways
- •When hindlimb lameness fails to respond to regional anaesthesia of the limb itself, consider referred pain sources—caudal rib fractures should be on your differential list
- •Use local anaesthetic blocks around suspected rib fractures to confirm they are the pain source before committing to long rest periods
- •Gamma scintigraphy is valuable for identifying occult caudal rib fractures that may not be obvious on physical examination or standard imaging
Key Findings
- •A caudal rib fracture (18th rib) caused moderate ipsilateral hindlimb lameness in a young Thoroughbred that did not respond to regional hindlimb anaesthesia
- •Gamma scintigraphy identified the rib fracture with focal increased radiopharmaceutical uptake and abnormal rib contour
- •Local anaesthetic infiltration around the rib fracture site completely abolished the hindlimb lameness, confirming the diagnosis
- •The horse returned to soundness 12 months after presentation following 12 weeks of rest