Fistulous withers causing spinal epidural abscess in a Thoroughbred mare

This case describes a 15-year-old Thoroughbred mare with fistulous withers that progressed to vertebral osteomyelitis and spinal epidural abscess (SEA), a severe complication that has yet to be reported. Initially treated with antibiotics and anti-inflammatory medication, the mare developed acute hindlimb ataxia and spastic paresis, suggesting spinal cord compression at T3-L3. Diagnostic imaging revealed vertebral fractures and abscessation, but vertebral canal involvement could not be confirmed. Despite aggressive medical therapy, including antimicrobials, corticosteroids, and neuroprotective agents, the mare's neurological condition deteriorated, leading to euthanasia. Post-mortem findings confirmed an extensive paraspinal abscess that had extended into the epidural space, causing severe spinal cord compression. The isolated pathogen, Escherichia coli, is commonly associated with chronic fistulous withers. This case underscores the importance of considering SEA as a diagnostic differential in horses with chronic paraspinal infections that develop acute neurological decline. Due to diagnostic and treatment limitations in equine medicine, prognosis remains guarded, with early surgical intervention and targeted antimicrobial therapy likely being crucial for better outcomes.