Patellar luxation, or "loose knees," is a congenital disease where the kneecap often comes out of position. While this issue can be identified quickly as dogs will limp, skip, and have abnormal sitting positions, it may not be noticed until about six weeks of age, according to dog-walking site Wag. "Depending on the severity and movement of the patella, a vet may recommend surgery," Dr. Sarno said. "It also helps when owners support the treatment with joint supplements and pain-relief methods." Think: steroids, pain relievers, braces, and bandages. And even better, the prognosis is usually positive. Dogs can live with the disease while still leading a healthy, normal life!