Ultrasonographic diagnosis of septic arthritis of the distal interphalangeal joint in cattle.

Diagnosis of septic arthritis in the distal interphalangeal joint (SADIJ) is often difficult, particularly when arthrocentesis or probing of the joint space are inconclusive. The aim of this prospective study was to investigate the usefulness of ultrasonography in reinforcing a tentative clinical diagnosis of SADIJ in 60 Holstein-Friesian cows with septic arthritis in one distal interphalangeal joint (DIJ). The diagnosis of septic arthritis was based on the results of clinical examination and radiographic images, as well as surgical findings. The DIJ of the partner claw of the same foot and the normal DIJs of 18 healthy Holstein-Friesian cows were used as controls. Visualisation, echogenicity and flow phenomena of the synovial fluid were assessed ultrasonographically. The size of the dorsal pouch of the distal interphalangeal joint (DPDIJ) was determined by measuring two defined distances. The DPDIJ could be imaged in all cows with SADIJ, although the quality of the image varied from good (63%) or moderate (30%) to poor (7%). The echogenicity of the synovial fluid in joints with SADIJ did not differ from those of the partner claws. Flow phenomena were seen in only 30% of the DPDIJs with septic arthritis and in none of the DPDIJs of the partner claws. The DPDIJ was larger in DIJs with septic arthritis than in those of the partner claws and controls (P<0.05). The dorsopalmar/plantar distance of the DPDIJ indicated a suitable sensitivity (0.97) and specificity (1.0) for the diagnosis of septic arthritis when a threshold value of 6mm was used. Ultrasonographic examination of the DIJ appeared to be a reliable method for confirming a tentative clinical diagnosis of septic arthritis in cattle.