MRI Findings in a Young Boxer with Septic Physitis of the Humerus.

The MRI appearance of appendicular septic physitis has not been reported in small animals. MRI appearance of septic arthritis and osteomyelitis has been described in horses, and the use of MRI has been proposed as a diagnostic alternative to radiographs to allow for earlier diagnosis and treatment. MRI is also routinely used in human medicine for the diagnosis of osteomyelitis owing to increased accuracy of evaluation of the soft tissue involvement. In the case of a 5 mo old male boxer dog described here, radiographs were suggestive of the diagnosis of septic physitis, although an MRI was obtained to rule out neurologic etiologies of lameness based on history and physical exam findings. MRI identified a fluid pocket communicating with the physis. The diagnosis of septic physitis was then confirmed via ultrasound-guided fine-needle aspirate of the fluid pocket communicating with the physis that was seen on the MRI.