LAMENESS: ITS CAUSES AND TREATMENT, 309 
mals the onset and progress of mysterious and unrecognizable ail- 
ments will at times bafile the most skilled veterinarian, and leave our 
burden-bearing servants to succumb to the inevitable, and suffer and 
perish in unrelieved distress. 
DISEASES OF BONES. 
PERIOSTITIS, OSTITIS, AND EXOSTOSIS. 
From the closeness and intimacy of the connection existing between 
the two principal elements of the bony structure while in health, it 
frequently becomes exceedingly difficult, when a state of disease has 
supervened, to discriminate accurately as to the part primarly af- 
fected and to determine positively whether the periosteum or the 
body of the bone is originally implicated. Yet a knowledge of the 
fact is often of the first importance, in order to obtain a favorable 
result from the treatment to be instituted. It is, however, quite evi- 
dent that in a majority of instances the bony growths which so fre- 
quently appear on the surface of their structure, to which the general 
term of exostosis is applied, have had their origin in-an inflammation 
of the periosteum, or enveloping membrane, and known as periostitis. 
However this may be, we have as a frequent result, sometimes on the 
body of the bone, sometimes at the extremities, andl sometimes in- 
volving the articulation ‘itself, certain bony growths, or exostoses, 
known otherwise by the term of splint, ringbone, and spavin, all of 
which, in an important sense, may be finally referred to the perios- 
teum as their nutrient source and support, at least after their forma- 
tion, if not for their incipient existence. 
Cause.—It is certain that inflammation of the periosteum is fre- 
quently referable to wounds and bruises caused by external agencies, 
and it is also true that it may possibly result from the spreading 
inflammation of surrounding diseased tissues, but in any case the 
result is uniformly seen in the deposit of a bony growth, more or less 
diffuse, sometimes of irregular outline, and at others projecting dis- 
tinctly from the surface from which it springs, as so commonly pre- 
sented in the ringbone and the spavin. 
Symptoms.—This condition of periostitis is often difficult to deter- 
mine. The signs of inflammation are so obscure, the swelling of the 
parts so insignificant, any increase of heat so imperceptible, and the 
soreness so slight, that even the most acute observer may fail to find 
the point of its existence, and it is often long after the discovery of 
the disease itself that its location is positively revealed by the visible 
presence of the exostosis. Yet the first question had been resolved, 
in discovering the fact of the lameness, while the second and third 
remained unanswered, and the identification of the affected limb 
and the point of origin of the trouble remained unknown until their 
-palpable revelation to the senses. 
