WEST OF ENGLAND VETERINARY MEDICAL ASSOCIATION. 217 
i 
do or from a want of judgment on the part of the rider or driver 
in going at too great a pace for too long a distance on hard roads, 
also pulling up too suddenly. 
Bad shoeing is a predisposing cause, as by it the foot and leg 
are often thrown out of the natural position, especially by the 
use of high calkins, which tend to produce concussion. 
In the early stage of the disease it often happens that the 
lameness or stiffness is very slight, and only observable when the 
horse is first brought out of the stable in the morning or when he 
is first made to turn over from one side of the stall to the other, 
and these symptoms may often be temporarily removed by a dose 
of physic or a week's rest in a loose box. The same remark 
also applies to many chronic cases when anchylosis is going on ; 
the inflammation being of such a low character, there is very 
little pain attending it, but when the horse is put to fast work 
the inflammation becomes more active and the pain more 
acute. 
Pathology .—In the early stage of articular disease there is a 
congested state of the vessels of the bone or bones of the hock, 
and if sufficient rest is not allowed for the vessels to recover 
their tone, inflammation of a persistent character supervenes, and 
the nutrition of the bones is then interfered with, as well as the 
secretion of synovia. This stage of the disease causes an aching 
pain, which interferes more or less with the action of the animal. 
Now, this state of things may exist for months with but slight 
lameness, and that of an intermitting character, or only to be 
observed for a few yards when the horse leaves the stable in the 
morning. If the animal is not properly treated and this inflamed 
state be allowed to exist for a long time, the destructive action 
commences by softening and enlargement of the central cancellated 
structure of the bone, the cells break up, absorption takes place, 
producing the first stage of molecular death, or what is termed 
dry caries, the progress of which depends much upon how the 
animal is used. Granular degeneration of the interosseous 
ligaments and articular surface of the cartilages commences, and 
soon afterwards a yellow plastic matter is thrown out, gluing the 
diseased part of the two bones firmly together. In this stage of 
the disease there will generally be more or less lameness or stiff¬ 
ness until the cartilaginous surfaces are nearly or entirely 
liquified and absorbed, and replaced by a bony matter; this is at 
all times a very slow process. The vessels of the bones throw out, 
from their roughened surfaces, bands of lymph, which by a further 
procegs become converted into bone, forming an anchylosed 
joint. If during this destructive and reparative process the horse 
is much worked, periostitis will be set up, so that in addition to 
the process going on between the articular surfaces of the joint 
