The prevalence of canine patellar luxation in three centres. Clinical features and radiographic evidence of limb deviation.

The medical records of 155 dogs with patellar luxation (PL) from three different centres were analysed. Each case was classified according to the nature of its luxation and any concurrent orthopaedic conditions plus the age at diagnosis were also noted. Measurements relating to angle of inclination (AOI) of the femoral neck and medio-lateral bowing of the femur and tibia at the stifle were also recorded. The femoral and tibial data were compared to dogs with another orthopaedic condition in a case-control assessment. Labradors were most commonly affected (21%). Most luxations were medial (92%) and 54% of affected dogs were female. The mean AOI of the hip was 148.95 degrees . There was a statistically significant difference between the stifles of dogs with PL compared to a control population. This study concluded that PL in large breeds is increasing. Lateral luxation was uncommon and was not associated exclusively with large breeds. Females were more likely to have PL than males and being female was a risk factor associated with coxa valga. There are significant differences in medio-lateral stifle conformation between dogs with PL and control dogs.