5-year-old spayed female Border Collie

Agility dog with 3 month history of left stifle lameness

  • Successful candidates recognized the caudal displacement of the tibial plateau, and more specifically intercondyle eminences, relative to the femoral condyles. Mild increased intracapsular soft tissue was considered a minor finding. Candidates possessing knowledge of this disease process also interrogated the area of the collateral ligaments, which can be compromised in this disease.
  • Unsuccessful candidates were numerous resulting in a 60% case average (or 4.8/8 as there were no management points). They fell into two categories; those who identified the displacement but did not synthesize it into the appropriate disease process and those created abnormalities seen in agility dogs. For those that identified the displacement, the examiner’s impression was an inability to fathom this uncommon disease. Even though the abnormality was identified, these candidates lost synthesis points and failed the case. Some these candidates would then transition into the second group and fail the case. Disease processes given to this case by candidates included gastrocnemius enthesopathy and myositis, lateral patellar subluxation, lateral femoral osteochrondrosis, or trauma to the popliteal sesamoid bone. Those selecting patellar subluxation failed to recognize the mild obliquity of the craniocaudal image. Those diagnosing gastrocnemius enlargement presumed to be myositis misinterpreted the alteration produced by the tibial displacement.
  • MRI was performed and confirmed the absence of any other derangement within or external to the stifle joint, except for a complete caudal cruciate ligament rupture at the distal insertion.