670 
ON CARPITIS. 
admitting of rest like the lateral joints, and the constant pressure 
keeping up the diseased action. 
The bones situate on the inner side of the joint are the most 
generally affected : from their being more under the centre of gra- 
vity they receive a larger portion of the weight sustained by the 
fore extremities than the bones on the outer side of the joint; 
therefore the bones more especially the seat of disease are the 
scaphoid and lunar of the upper, and the trapezoid and os magnum 
of the lower row ; also the head of the inner small metacarpal 
bone, and that portion of the articular surface of the large metacar- 
pal which corresponds to the os magnum, more particularly towards 
its inner margin. I have often found that, while the bones situate 
on the inner side could only be separated by fracture, those on the 
outer have not been at all united by ossific matter. 
It will also frequently occur, that the trapezoid and os magnum 
are united by osseous deposit to the heads of the large and inner 
small metacarpal bones, and this without any connexion with 
splent. It is a common remark, that a splent is only of serious 
consequence when it is situate close to the knee joint : in fact, this 
form of carpitis has been confounded with splent ; and though the 
disease will extend to the inner small metacarpal bone, it will be 
found to affect only the head and its articular surface, and must 
not be confounded with true splent. 
I think it probable that the existence of splent is the precursor 
of that form of carpitis which affects only the trapezoid and head 
of the inner small metacarpal : from this latter bone not being able 
to perform its function, the bone immediately resting upon it 
receives a greater degree of compression than it is capable of en- 
during, more especially during that period when the bones are still 
soft from not having arrived at maturity, or in those animals 
which have their bones naturally of a soft texture, such as is often 
seen in under-bred horses : in old horses, the bones of which are 
of a firm texture, and have been long the subjects of splent, 
Nature provides for this alteration by the diminution of that part 
of the body of the trapezoid which rests upon the head of the 
small metacarpal, or of the head of that bone itself, by which 
means much of the concussion which would otherwise occur is got 
rid of. 
It is but rare to find that the disease extends to the joint 
formed by the os brachii and upper row of the carpus. 
There is but one other observation I have to make, that is, to 
the disease of the joint dependent upon external injury. This is 
most frequently the result of broken knees, either from the severity 
of the injury, or from putting the animal too soon to work after 
