Patella luxations (dislocation of the knee-cap) occur frequently in dogs.
Patellar luxations can be grouped into two main categories.
First, and most commonly, is medially luxating patellas (MLP) which are congenital (existing from birth) these commonly affect smaller breeds of dogs.
The second type is laterally luxating patellas, which are often the result of trauma. Lameness occurs as the patella luxates and often resolves when it spontaneously reduces. Lameness is often intermittent as animals learn to reduce the patella themselves by extending the hip and the knee together behind them.
Diagnosis is made by physical examination and may be confirmed with an x ray, x ray's will demonstrate the patella luxation if the patella is dislocated. All animals with patellar luxation can develop some degree of arthritis.