Roughly speaking, sesamoid lameness is a condition of the gliding surface of the sesamoids, and the face of the tendon playing over them, similar to that found in navicular disease. All symptoms of pointing, the constant maintaining of the limb in a state of flexion, and a feeling manner of progression are again all present. It is plain from this that in all cases where an animal with a gait at all suggestive of navicular disease is brought for our examination, the manipulation of the limb should be thorough. The character of the lameness is almost sure to deceive us; and it is not until we are able to obtain local symptoms pointing to the one or the other of the conditions we have enumerated that a decisive opinion may be given. In sesamoid lameness the local symptoms are those of heat and pain in the fetlock on palpation, and a swelling of the affected parts, such swelling being at first slight, yielding, and barely distinguishable, and afterwards larger, bony and hard, and more marked. Later still there is distinct evidence of 'knuckling' over at the fetlock and inability to fully flex it. In cases of shoulder lameness the gait alone should be sufficient to render liability of error small, for with nearly every case there is a manifest inability to 'get the limb forward', and this is best seen at a side view when the animal is trotting past the observer. When trotting towards one, there is a further and unmistakable symptom common to most shoulder lamenesses that serves to distinguish it at once, and that is the peculiar 'sweeping' outwards with the affected limb. Lastly, with either of the conditions we have just mentioned, it is the exception to get contracted foot follow on. With navicular disease it sooner or later makes its appearance. _Prognosis_.--The prognosis of navicular disease (once diagnosed with certainty) must almost of necessity be unfavourable. The facts that the disease has made serious progress before it is really noticeable, that the situation of the parts prohibits operative interference, and that the disease is one of a chronic and slowly progressive type, all point to an unfavourable termination. _Treatment_.--We have seen from the pathology of this disease that it may commence either as a rarefactive ostitis, or as a synovitis and tenositis in connection with the bursa. With the former condition in existence, or when this and the synovitis has led to erosion of the cartilage, treatment is probably of no avail, on account of the more chronic nature of these two conditions. When, however, the condition is simply that of synovitis or tenositis, a more or less acute condition, we may assume that suitable treatment and a long rest will bring about resolution.