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Medial Patella Luxation in Dogs - Page 1 MPL can occur as a result of trauma or develop during the first year of an animal's life. Congenital or developmental MPL is more common. It is most commonly found in a wide variety of small dogs such as poodles, Yorkshire terriers, Maltese and bichon frise, but it also occurs in larger breeds. Animals may present when they are young, during the first year of life, particularly if the abnormality is severe, or any time later in their life if the problem is lower grade and leads to a more progressive, chronic lameness.