Clinical history - Radiographs were made of the left tarsus because of acute lameness of short time

An enlargement of two views

Radiographic diagnosis

Multiple views of the tarsus offer the opportunity for comparison of the affected distal intertarsal joint with the other joints. The major radiographic feature is the widened radiolucent joint space with destruction of the subchondral bone with a margin of increased bone opacity forming peripherally. The periarticular region of the affected joint is partially bridged with new bone tissue that is seen to be incomplete at this time especially on the craniolatero - caudomedial oblique The diagnosis is an acute bone spavin.

Comments

• This example of high stress‐low motion arthrosis (bone spavin) is unique, appearing usually in the intertarsal joints, proximal interphalangeal joint, and involving the navicular bone.
• A diagnosis of infectious arthritis can be entertained because of the destructive nature of the disease as seen at this time. However, the uniform destructive appearance seen in this horse is typical for this type of non‐infectious arthrosis in a low‐motion joint and will be followed by bony fusion later with a suggestion of diminution of clinical signs.
• See the following case.

• A mature spavin in another horse with bony fusion of the distal intertarsal (centrodistal) joint
• No signs of active periosteal new bone is seen bridging the joints
• Compare the radiograph of this patient with chronic disease with the patient above that has active disease