DISEASES OF THE BONES 393 
covery by finding gradual improvement for a time by 
fomentation and poultices, followed by irrigation and 
stimulants to the coronet, and perhaps the animal is dis- 
charged 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 
Fic. 153.—Errects oF PERIOSTITIS ON THE Os PEDIS. 
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. 
‘Treatment.—It is obvious from the position of this 
