Diagnosis The major problem in this case is the medial luxation of the right patella. Examination under sedation and radiographs showed that there are no other obvious pathological processes going on in this dog. It is difficult to determine if this case is strictly related to trauma or if it is purely congenital, and our best diagnosis would likely involve a combination of the two (hypothesis 1 and hypothesis 2, minus the cranial cruciate ligament rupture). Trauma- induced medial patellar luxation is indeed common in Pomeranians and most of the symptoms this dog exhibited match the typical expected symptoms. In traumatic cases, symptoms are slow to develop. The major problems are mostly seen later in life, long after the original insult. Traumatic cases are usually a grade 1 to 2 luxation, with a greater degree of functionality than other pathologic processes. Clinical signs usually develop quickly following a second minor trauma or strenuous activity. In TitanÕs case, it is likely that the original insult occurred from jumping off the bed, and the continuous play with the other dog in the household may have acted as the strenuous activity which brought on the more severe clinical signs. Congenital medial patellar luxation may have also played a role in this case by predisposing Titan to the luxation following a slight traumatic event. This abnormality is common in Pomeranians and other toy or mini breed dogs. The one aspect that suggests it may not be a congenital problem is that they usually present with other pelvic limb deformities, which are not present in this case. What probably happened with Titan is that a slight congenital problem predisposed her to have a luxating patella in the right leg. When she jumped off the bed, the patella popped out of the trochlear groove and cartilagenous surfaces were rubbing against each other abnormally. Little or no discomfort was shown until cartilage was significantly damaged; in this case it showed up several months following the trauma. Once it reached this point, the luxation elicited more of a pain response, and the dog was presented to the clinic. At this point, when the patella luxates out of position, the dog may cry out and extend the leg to pop it back into position or hold the limb up until muscle relaxation allows the patella to regain itÕs normal position. This may be the reason Titan has been showing intermittent lameness rather than persistent lameness.