Septic arthritis and osteitis of the left C4–C5 articular process joint in a 4‐month‐old colt with neck stiffness

Summary A 4‐month‐old warmblood colt presented with an acute onset change in gait and mentation. Neurological examination identified marked cervical stiffness with bilaterally reduced lateral flexion, pain on palpation of the mid‐caudal cervical region and mild positional strabismus when the head was elevated. Radiography and ultrasonography of the C4–C5 articular process joint, respectively, revealed a large radiolucent defect within the left caudal articular process of C4 and distension of the synovial recesses containing hyperechoic, heterogeneous fluid. Ultrasound‐guided synoviocentesis yielded a purulent sample with a white cell count of 131 × 10 9 /L (reference range: <2 WBC/μL) confirming the presence of septic arthritis. Computed tomography was used to evaluate concurrent osteitis of the C4 caudal articular process. Arthroscopic lavage of the affected joint was performed under general anaesthesia, followed by peri‐ and postoperative antimicrobial therapy. The foal recovered uneventfully, showing no residual neurological or musculoskeletal deficits up to 15 months postsurgery. This report describes successful surgical management and clinical resolution of cervical articular process joint sepsis in a foal, achieved through timely diagnosis and intervention.