For the first time in veterinary literature, magnetic resonance and arthros
copic features of a discoid lateral meniscus in a dog are described. A 15-m
onth-old Labrador Retriever with a history of mild intermittent left hindli
mb lameness was referred to our clinic. Physical examination revealed mild
joint effusion of the left stifle and absence of a cranial drawer motion an
d tibial compression test. Survey radiographs demonstrated mild joint effus
ion and peri-articular new bone formation. Low-field magnetic resonance tom
ography of the left stifle joint demonstrated injury of the cranial cruciat
e ligament and a discoid lateral meniscus. Two weeks later, arthroscopy rev
ealed a partial tear of the cranial cruciate ligament with mild synovitis.
Furthermore. some fibres inserted abnormally cranial to the inter-meniscal
and cranial tibial ligament of the medial meniscus. The lateral meniscus wa
s discoid in shape. Subsequent arthrotomy confirmed the diagnoses. Discoid
meniscus is a rare finding in the dog with unknown clinical relevance where
as it is well known in humans.