Glossary
Luxating patella
A condition in which the kneecap slips out of its groove, common in small breeds and often seen as a brief hop or skip in the stride.
Also called: patellar luxation, slipping kneecap, trick knee, skipping dog
The patella, or kneecap, normally glides in a groove at the end of the thigh bone. In a luxating patella it slips out of that groove, usually toward the inside of the leg, and the dog may skip, hold the leg up for a few steps and then run normally again.
It is especially common in toy and small breeds such as the Chihuahua and Yorkshire Terrier, and it is often inherited. Vets grade it from 1, where the kneecap pops out only when pushed by hand, to 4, where it stays out and the leg is held bent.
Mild cases may need only monitoring and weight control, but repeated slipping can wear the joint and strain other ligaments. A veterinarian decides whether a dog needs surgery.
Last reviewed November 8, 2026