Ever since my Chihuahua was a puppy, he constantly switches back legs when running. Some times, he runs on all fours. Other times, he will run on 3 legs, always keeping one back leg off the ground. When he does this, it is never the same leg, and some times he switches. He never shows any signs of discomfort or yelps that might indicate pain. We even took him to the vet when he was young and they checked his knees and they did not detect anything. They said smaller breed dogs may do this "just because they can get away with it." However, I was doing some reading today and came across this link on wikipedia about luxating patella. It states
Chihuahuas are also known for luxating patella, a genetic condition that can occur in all dogs. In some dogs, the ridges forming the patellar groove are not shaped correctly and a shallow groove is created, causing the patella to luxate or slip out of place, sideways. The knee cap sliding across the bony ridges of the femur can cause some pain. The affected chihuahua will hold its leg flexed, and foot off the ground until the quadriceps muscle relaxes and lengthens, after which the animal feels no discomfort and continues with activity.
Emphasis my own. This seems to describe what occurs. But he doesn't have any issue walking, and like I mentioned no indication of pain. Did my vet know what he was talking about? Or should I be concerned?