Panosteitis, or Pano as it is commonly called, is a disease which affects the long bones in growing young dogs, mostly of the larger breeds, but occasionally is seen in some smaller breeds as well.  German Shepherds are one of the breeds who are often presented with lameness and limb pain between 5 and 18 months of age, and many veterinarians diagnose Pano as it's cause.

The first signs of Pano are often a slight lameness in one leg, progressing to a severe limp and possibly non-use of the affected leg.  It may last for days to weeks, and may seem to resolve then recur in the same leg, or another one.  Some dogs can exhibit lameness in more than one, or even all legs at the same time. Often Pano shows up in a foreleg first.   Bouts of lameness can come and go, seemingly for months.   Some dogs suffer from Pano off and on until they are nearing 2 years of age or even beyond.  I believe a case has been documented in a 5 year old dog, but that is unusual.  Most cases start near the end of rapid growth, about 5 to 6 months of age, and are cleared up by 12 to 18 months of age.  Males seem to be more affected than females, but both sexes can exhibit signs.

Radiographic signs, those seen on an x-ray, can be elusive when diagnosing Pano.  The bones most affected are the radius and ulna (the foreleg), the humerus (upper arm), the femur (thigh) and the tibia (lower rear leg). Pano is an inflammation of the bone itself, the cortex (outer shell) becomes less distinct and foggy, and the interior of the bone seems to increase in density.