Introduction Medial patella luxation is a condition in which the patella (knee-cap) no longer glides within its natural groove (sulcus) in the femur, the upper bone of the knee joint. It becomes displaced to the inside or outside of the joint and can be partial or complete, intermittent or permanent. Medial patella luxation can occur as a result of trauma, or develop during the first year of an animal's life. Medial patellar luxation usually occurs in toy breeds of dog, and may be unusual in cat, especially in Domestic Shorthair. Materials & methods A 2.5 year-old Domestic Shorthair cat, was admitted to the Clinic of Veterinary Medicine, Ferdowsi University of Mashhad with a complaint reluctance to jump or to walk down a slope. On physical examination, palpation of the left stifle joint revealed medial patellar luxation. The patella was luxated permanently, but could not be reduced to its natural groove manually. After clinical examination, radiography in medio-lateral, cranio-caudal & Skyline views were carried out. Results Lateral radiograph, was shown patella out of the trochlear groove of left femoral bone and superimposed with the femoral condyles. In medio-lateral view, the fibula was seemed in medulary cavity of the tibia that was due to tibial rotation medially. Skyline view was shown patella in the medial side of left femoral epicondyle. Accourding to physical and radiologic examination, medial patellar luxation in left leg with a grade IV was confirmed. Conclusion This case is reported because patellar luxation has been seen in DSH cats unusually.

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