Owner's Complaint Not using left back leg properly - helps localize lameness Signalment Canine, Labrador retriever - large breed dogs are more prone to certain disorders Female, spayed, 6 years old - age and gender, make a congenital disease less likely, but still possible Present History Does not get up as you enter the room - may indicate lameness; may indicate laziness First time dog has been hurt in 5 years - osteoarthritis is often a sequelae of injuries Has been lame since Wednesday - acute onset Favoring left hind leg - localizes lameness Difficulty getting up and down stairs - indicates extent of lameness Past History Adopted from humane society (history unknown) - genetics unknown Fed 4 cups of Hills Adult Maintenance with occasional treats - nutritional deficiencies Normal annual check ups - no chronic problems noted until now Up to date on vaccines - infectious causes less likely Very active dog - rules in trauma, strain, etc. Physical exam Partial weight bearing left hind limb lameness - indicates extent and localizes lameness Barely toe touching with L hind leg when standing - indicates extent and localizes lameness Effusion of the Left stifle joint with a distention of the joint capsule on either side of the straight patella ligament - indicates patellar ligament problems unlikely, effusion indicates inflammation of stifle joint Pain on manipulation of the stifle - indicates nerves to stifle area are intact Overweight - predisposes to many orthopedic conditions, since it can turn physiologic forces into pathologic ones No cranial drawer can be palpated in the stifle while patient is awake - may not be significant While under sedation a 4-5m cranial drawer can be palpated in the L stifle with a less than 2mm palpable in the right - indicates instability in the left stifle, highly indicative of cranial cruciate instability Colllateral ligaments are intact - rules out collateral ligament tear, and stifle dislocation Hip joints have no palpable laxity or pain - rules out coxofemoral joint problems No other abnormalities could be found - helps localize lameness, since no medial buttressing is found or joint capsule thickening, cranial cruciate instability is likely to have been recent, since a previous tear/instability would have resulted in fibrosis to stabilize the joint.