996 
S. J. J. HARGER. 
lesions remain in that condition for a more or less long time or, 
merely the beginning of a condition that spreads to other bones 
and subsequently manifests itself by an external enlargement. 
The time required for the latter to become visible on the exterior 
is usually said to be from six weeks to two months. Spavin 
therefore seems to develop eccentrically, beginning within the 
, internal bony structure and the articular surfaces. 
We cannot deny the probability of spavin commencing as a 
periostitis in cases of traumatisms and hyperextension of the 
internal ligaments of the hock joint, but that this is not the 
general mode. It also appears to me that these are not the 
usual causes, but that the latter operate incessantly at every step 
the animal takes in the form of constant concussions transmitted 
through these bones, the perpendicular pressure of one bone 
upon the other and the traction of the interosseous ligaments. 
Relative to inheritance in which there is a defect in the organi¬ 
zation and integrity of the intimate structure of bone—an 
osteitic diathesis—the hock bones are subjected to the injurious 
effects of these constant causes and thus become diseased more 
readily. 
Very recent cases of undoubted hock lameness without visi¬ 
ble external alterations often respond to the effects of a good 
blister. Having said that such diseased conditions of the hock 
are primarily articular, I do not mean to convey the idea that the 
blister cures by producing ankylosis, such as cauterization does. 
These cases only present a sort of nerve irritation, the primary 
symptoms of inflammation without any decided structural 
changes, and the treatment is efficacious through its revulsive 
action, a possible reflex action through the nerve trunks in cor¬ 
recting the pain and the circulation, and the immobilization of 
the parts. 
From a comparison of the external aud internal lesions of 
ringbone and spavin we find the conditions in the two reversed, 
the former developing from without to within and the latter 
from within to without, the enlargement of the hock being sec¬ 
ondary. While some of the distinctions which I have here 
