Osgood-Schlatter disease in an English setter.

Dear Sir, The question whether Osgood-Schlatter disease (OSD) exists in the dog was raised in your journal four years ago (1). D. von Pfeil et al. concluded that the term OSD was not appropriate to use for dogs, as traction injuries to the tibial tuberosity were not found to cause the pathognomonic calcified particles within the distal aspect of the patellar ligament in this species (1). Subsequent case reports concerning OSD in dogs have not been found. We hereby wish to inform you about a young dog with clinical signs, radiological changes, and ultrasonographic findings corresponding to true OSD. A twenty-month-old, 20 kg, male English Setter was referred to the Norwegian School of Veterinary Science (NVH) for evaluation of intermittent bilateral pelvic limb lameness. According to the owner, the lameness had begun fifteen months prior to admission and was most obvious on the right pelvic limb. No restrictions had ever been put on the dog ́s desire to run. On referral, the dog showed shortened pelvic limb strides while walked and trotted on a leash. He could change posture carefully from a standing into a normal sitting position. Limb palpation revealed swollen and painful stifle joints and tibial tuberosities. The most obvious pain response was provoked by maximally extending the right stifle joint. Plain lateral and caudocranial radiographs of the stifles showed ossicles at the patellar ligament insertion, swelling of the patellar ligament and joint effusion, bilaterally (▶ Figure 1 a and ▶ Figure 2 a). On ultrasonographic examination, a significant thickening of the distal ca. 1.5 cm part of both patellar ligaments was identified. The thickened ligamentous tissue showed a considerable reduction of echogenicity, an absence of collagen fibre parallelism and contained several hyperechogenic (calcified) structures. On the basis of clinical history, orthopaedic examination, and diagnostic imaging a diagnosis of bilateral OSD was made. Shockwave therapy was offered, but the owner declined and elected conservative treatment including exercise moderation and long-term antiinflammatory medication. At a check-up two months later, the dog ́s clinical signs were unchanged. Plain radiographs were repeated and revealed further development of the patellar ligament ossicles at both stifles (▶ Figure 1 b and ▶ Figure 2 b). The owner considered the dog to be in good shape and therefore rejected any treatment but continued exercise moderation. One year after the first referral, the dog (now 25 kg) was readmitted to the NVH for a second check-up. On readmission, the dog ́s clinical signs were similar to those observed at the initial examination with the exception of