There is frequent
patellar luxation which, in some cases, becomes more or less permanent. The
limb is sometimes carried, although weight bearing routinely occurs with the
stifle remaining slightly flexed.
Especially under anesthesia
it is often possible to reduce the luxation by manually turning the tibia
laterally, but the patella reluxates with ease when manual tension of the
joint is released.
As much as 30 degrees of
medial tibial torsion and a slight medial deviation of the tibial crest may
exist. When the patella is resting medially the hock is slightly abducted.
If the condition is bilateral, more weight is thrown onto the forelimbs.
Many cases in this grade
live with the condition reasonably well for many years, but the constant luxation
of the patella over the medial lip of the trochlea causes erosion of the
articulating surface of the patella and also the proximal area of the medial
lip. This results in crepitation becoming apparent when the patella is luxated