Epiphysis is the growing end of the bone and diaphysis is the shaft of the long bone. The metaphysis is the conical part of the bone between the epiphysis and the diaphysis. The physis is the epiphysial cartilage in the joints joining the parts of the bone into one. This is the soft, connective part of the bone that hardens or ossifies after full growth has been reached.
Puppies suffering from Hypertrophic osteodystrophy show an inflammation of the bony spicules which are pointed, mineral structures in the metaphysis of the long bones. Widening of the metaphyses is caused due to the swelling around the metaphyses and bone deposition. Tiny fractures of the bony spicules in the metaphyses and metaphyseal separation occur close to and parallel to the physis. This may be accompanied with ossifying periostitis, a painful inflammation of the most external layer of the bone called the periosteum. Ossifying periostitis can cause bits of the periosteum to break off and mineralize in the soft tissues of the leg, and soft tissue in other organs may mineralize as well.
The bones are those that grow rapidly are the ones that are most severely affected. The condition is primarily seen in the front limbs in large-breed puppies.
Affected puppies may also have accompanying signs of pneumonia and diarrhea. Other common symptoms include lameness, most often in the forelimbs, reluctance to move, warm & swollen metaphyses, high fever, depression, lack of appetite, weight loss, dehydration, diarrhea, and pneumonia.
