Well, cr@p! It looks like Zaccheus has Legg-Calve-Perthes Disease. It is in the very early stages, and we will be managing it for a while with anti-inflamatory drugs and joint support suppliments.
Here's what I found when I googled it:
"Avascular necrosis of the femoral head, aseptic femoral head necrosis, or Legg-Calve-Perthes disease is a disorder of the blood supply to the femoral head, the "ball" of the hip joint. It usually occurs in miniature and toy breeds of dogs between the ages of four months and a year of age in its classic form but sometimes occurs as a traumatic problem in older dogs or bigger breeds. It causes death of the bone which leads to arthritis of the hip."
"Femoral head necrosis is a painful process and may be a cause of subtle lameness to total lameness affecting one or both rear legs. Some dogs are able to recover on their own with just rest and pain relief but many dogs require surgical removal of the femoral head (femoral head ostectomy) for good long term pain relief. This can be done on both sides, if necessary, in the small dogs who have this problem."
Unfortunately, surgery is not an option for us financially right now, but Doc says he wouldn't even recommend it today if we could. He's got at least a year, maybe two or three before he will be advanced enough to need it. By then, hopefully we can be ready.