[Illustration:  FIG. 151.—­EFFECTS OF PERIOSTITIS ON THE PEDAL AND NAVICULAR BONES.]

’It should also be noted that the animal was able to undergo a severe course of training for some years, and to gallop successfully over some of the most trying courses in England.  During the whole of this time he walked and galloped apparently sound, but trotted always lame, and generally dead lame.’[A]

[Footnote A:  W. E Litt, M.R.C.V.S., Veterinary Record, vol. viii., p. 527.]

[Illustration:  FIG. 152.—­EFFECTS OF PERIOSTITIS ON THE OS PEDIS.]

2.  ’I herewith send you photographs of three cases of the above disease, occurring in the internal surfaces of the wings of the os pedis.  The photos were kindly done for me by Dr. A. Lingard, Imperial Bacteriologist to Government of India.  It is a cause of many cases of obscure foot lameness in India, and frequently accounts for the numerous entries on veterinary medical history sheets under the heading “Contused Foot.”

’The course of the disease is as follows:  The disease makes its appearance very soon after arrival in India, the animal being admitted to hospital suffering with undoubted foot lameness, generally slight.  One is soon led to suspect this disease by negative symptoms of other disease being in existence.  No coronary enlargement or flinching on pressure to the coronet, no shrinkage or wiring in of the heels, neither is the characteristic pointing of navicular present.  In the early stages one has false hopes of recovery by finding gradual improvement for a time by fomentation and poultices, followed by irrigation and stimulants to the coronet, and perhaps the animal is discharged from hospital, to be returned after a few days worse than ever.  The disease then becomes insidious and more pronounced, the nodding of the head, even at a walk, more exaggerated, and, in fact, the animal seems afraid to put his foot to the ground, and much resembles a horse with an abscess in his foot, either from prick or picked up nail.  He absolutely nurses his foot.  There is a certain amount of heat always present.  The disease being now well developed, pressure is caused by the ends of the navicular bone, and they become involved at their points by bony deposits.  The causes of this disease I attribute, firstly, to hereditary predisposition; and, secondly the exciting cause, standing confined on board ship, where no doubt pedal congestion takes place.  And perhaps some subjects start it in their marches in mobs down country in Australia.  Concussion may be the cause among older horses, but the specimens photographed were taken from remounts, that had either done no work or only very gentle work, in a deeply littered riding school.

[Illustration:  FIG. 153.—­EFFECTS OF PERIOSTITIS ON THE OS PEDIS.]

’Treatment.—­It is obvious from the position of this disease that treatment will be of no avail in producing a cure.  As already stated, the disease is insidious and progressive, and it is hopeless to expect to arrest the growths once they are started.  Unnerving would no doubt remove the symptom (lameness) of the disease, but an unnerved horse is not of much good for army purposes.  I therefore consider that once the disease becomes firmly established it is an unfortunate and incurable one.