The parts are just wearing out.
The problem can occur anywhere there are
joints in
the body, which include her spine, hips, knees, ankles, feet, shoulders, elbows, wrists, and even in her tail. Lyme disease can contribute to joint pain and should be checked often and treated if necessary.
Nonsteroidal anti-inflammatories such as Rimadyl or Previcox do help with joint pain and work to decrease inflammation which can further help to deteriorate joints.