Trapped Neutrophil Syndrome in a Border Collie

A 10 wk old female border collie was presented for hemorrhagic diarrhea and pelvic limb lameness. Examination revealed pain and effusion in multiple appendicular joints and pyrexia. Clinicopathologic testing revealed moderate neutropenia as well as nondegenerate neutrophilic inflammation in multiple joints. Radiographs showed capsular joint swelling and heterogeneous metaphyseal lucencies in the distal radius, ulna, femur, and tibia. Genetic testing confirmed a mutation in the vacuolar protein sorting-associated protein 13B gene and a diagnosis of trapped neutrophil syndrome (TNS). Within 24 hr of initiating prednisone therapy (1 mg/kg,