Navicular bone osteomyelitis and navicular bursitis with associated fistula diagnosed with magnetic resonance fistulography in the horse
Authors: Garcia E. B., Rademacher N., McCauley C. T., Gaschen L.
Journal: Equine Veterinary Education
Summary
# Editorial Summary A 7-year-old Quarter Horse with chronic hindlimb lameness localised to the foot presented with a previously unidentified draining tract at the plantar pastern, alongside radiographic evidence of severe navicular bone osteolysis. Conventional magnetic resonance imaging was complemented by positive contrast MR fistulography using gadolinium to establish the three-dimensional anatomy of the fistulous tract and its relationships to surrounding soft tissue structures. The imaging revealed a complex pathology involving osteomyelitis of the navicular bone with an associated fistula intimately connected to both the deep digital flexor tendon and navicular bursa—a combination that would be difficult to fully characterise using radiography or conventional MRI alone. This case demonstrates that contrast-enhanced fistulography provides superior definition of tract geometry and adjacent anatomical involvement, which is crucial for surgical planning and prognostication in cases of chronic foot lameness with drainage. For practitioners managing horses with unexplained chronic lameness and draining wounds in the palmar foot region, this technique merits consideration as it may reveal multi-system involvement that influences treatment strategy and realistic outcome expectations.
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Practical Takeaways
- •When a draining tract is identified in a lame horse's foot, suspect deep-seated infection involving the navicular bone or bursa and pursue advanced imaging
- •MR fistulography with contrast enhancement provides superior characterization of fistulous tracts and their relationship to critical structures compared to conventional radiography alone
- •Navicular bone osteomyelitis should be considered in cases of chronic foot lameness with radiographic evidence of bone lysis, even if fistulas are not initially apparent
Key Findings
- •MR fistulography using gadolinium contrast successfully characterized a fistulous tract associated with navicular bone osteomyelitis and navicular bursa involvement
- •The fistulous tract was closely associated with the deep digital flexor tendon, demonstrating anatomical relationships not apparent on conventional imaging
- •Severe osteolysis of the navicular bone was present with a draining tract at the plantar pastern aspect