Hock Arthritis in a Horse

A 14 year-old gelding presented to PHD veterinary services for the complaint of left hind limb lameness. The lameness had been noted for 6 months with minimal clinical improvement after several months of pasture rest. On presentation the gelding was a grade 3/5 lame in the left hind limb when trotted in a straight line. Flexion of the lower limb and upper limb did NOT worsen the lameness. In addition, the lameness did NOT worsen when lunged in either direction. Physical exam of the left hind limb did not identify any swelling or joint effusion however the gelding's range of motion of the hock joint was reduced. Radiographic evaluation of the limb was elected as the best option for identifying the source of lameness in this horse.  In Figure 1 and 2, the lower hock joints are identified as the following: PIT= proximal intertarsal joint, DIT= distal intertarsal joint, and TMT= tarsal metatarsal joint. 

Figure 1

Figure 2

In Figure 3, the lower hock joints are circled in blue and the yellow arrows are highlighting areas of significant arthritis across the front of the lower hock joints. For comparison, in Figure 4, the right hock is imaged in a radiograph and there is no evidence of arthritis in any of the hock joints.

Figure3

Figure 4

In Figure 4, the front of the lower hock joints appear disfigured (yellow arrows) by the advanced arthritis present. In addition, there is evidence of arthritis in the most proximal hock joint (tibio-tarsal joint) which significantly worsens the prognosis for this horse (Figure 4, red arrow).

Figure 4

The cause of such advanced arthritis in only one hock suggests trauma or a previous infection. Unfortunately, the full history of this horse was not available. Recommendations included a daily anti-inflammatory medication and intra-articular therapy with corticosteroids. Prognosis is guarded for soundness due to the involvement of the tibio-tarsal joint and the degree of arthritis noted in the lower hock joints.