A dog’s forelimb from the elbow to the wrist is comprised of two bones called the radius and the ulna.  The top end of the ulna has a curved indentation which allows the rounded bottom of the humerus (upper leg bone) to fit together and form a joint.  The top lip of this notch is called the anconeal process, and the bottom lip of this notch is called the coronoid process.  The use of the word process refers to the fact that this is a part of the bone that articulates, or moves, with another bone.

Limping, pain, standing with pasterns turned inward and toes out, standing or moving with elbows out, thickened elbows.

The AP is enclosed within the joint capsule and is only visible in x-rays taken from a specific angle with the elbow partially flexed.  

There are many different surgical options for AP.  Surgical removal of the fragment is possible, however, can result in instability of the joint and continued degenerative joint disease.  If the problem is diagnosed very early, the AP can sometimes be permanently fixed to the ulna.  Unfortunately, in many cases the AP is already too damaged for this repair by the time diagnosis is made.  Another possible option is ulnar osteotomy (surgical division or excision of the bone, or a portion of the bone) to relieve the pressure on the anconeal process.  In theory, with the pressure removed, the anconeal process can fuse normally.   This procedure, in appropriate cases, is reported to be very effective in restoring pain‑free use of the elbow and delaying the progression of DJD.  With any form of surgery, degenerative joint disease (DJD) is still likely to develop, but at a much slower rate.