Arabian foal 2 weeks of age Male Presented for swelling in the region of the right shoulder. Referred from private vet after treatment with antibiotics for suspicious of post natal umbilical infection. Radiographs of the shoulders were taken. Mediolateral view of the left (left image) and of the right (right image) shoulder. Radiographic findings There is a moderate to severe soft tissue swelling around the right shoulder, better visible cranially (arrow). The radioopacity of the proximal humerus is heterogenous compared to the left side, with ill defined bone sclerosis surrounding the physis of the ossification center of the humeral head and lesser tubercle (open arrows). The cranial periarticular border of the right scapula is more irregular than the left with a possible additional separated mineral opacity distal to the ossification center of the cranial part of the glenoid (arrowhead). Close up of the ML view of both the shoulder (left shoulder on the left). Radiographic diagnosis
- The signalement, the history and the radiographic appearance of the right shoulder (soft tissue swelling and bony changes with sclerosis) taken together are suspicious of septic arthritis and osteomyelitis, less likely differential diagnosis are other causes of joint effusion (hemoarthrosis, synovitis) and physitis.
- An ultrasonographic examination was performed, the joint effusion was anechogenic and graded as moderate.
- The synoviocentesis got fluid with cell count of 128000/μl.
- The horse underwent 3 arthroscopies (in the following week) with joint lavage and a large defect in the cartilage of the humeral head was visible.
- The therapy included immunoglobuline, antibiotics and antinflammatory administration.
Radiographic follow up Radiographs of the right shoulder were repeated after 5 weeks. The foal was clinically better and was weight bearing. ML view of the right shoulder Comments
- On the second radiographic examination the findings were progressive. There is a curvilinear mineral opaque linear opacity adjacent and parallel to the humeral head a more faint one following the articular surface of the scapula. An ill defined ovoid lucent defect is superimposed to the proximal humeral physis caudally and surrounded by a faint and irregular sclerotic rim.
- The cranial border of the articular surface of the scapula is irregular.
- The mineral linear opacities were interpreted as mineralisation of the articular surface, possibly at least partially dystrophic following drug administration.
- The prognosis is, considering the severe changes, very guarded.
- Septic arthritis of the scapulohumeral joint occurs most commonly in young foals and may result from osteomyelitis of the distal scapula or proximal humerus, or the humeral physis.
- In adult horse it is usually iatrogenic.
- Radiographic findings are lucent zones in the subchondral bone and irregular outline of the articular surface.
