Presumed septic sacroiliitis in a puppy with unilateral hind limb lameness and sciatic nerve neuropathy

A 5-month-old female entire Dachshund presented with an acute onset of left hind limb lameness following intense play. There were concurrent intermittent neurological deficits in the left hind limb, and pain in the lumbosacral region and on dorsal flexion of the tail. Computed tomography (CT) imaging revealed an asymmetric widening of the left sacroiliac joint with loss of cortical margins, accompanied by mild osteolytic changes of the adjacent ilium and sacrum highly suggestive of septic sacroiliitis. There was also perilesional steatitis in the region of the sciatic nerve. An 8-week course of antimicrobial therapy was prescribed. Complete resolution of all clinical signs was noted at a 7-month follow up. Sacroiliitis should be considered as a differential for unilateral hind limb lameness with or without intermittent sciatic neuropathy in a puppy in the absence of other orthopaedic conditions.