LAMENESS: ITS CAUSES AND TREATMENT. 857 
tion of the shank bone (the tibia) and one of the bones of the hock 
(the astragalus). The tendinous sac lies back of the articulation 
itself and extends upward and downward in the groove of that joint 
through which the flexor tendons slide. The dilatation of this articu- 
lar synovial sac is what is denominated bog spavin, the term 
thoroughpin being applied to the dilatation of the tendinous capsule. 
The bog spavin is a round, smooth, well-defined, fluctuating tumor 
situated in front and a little inward of the hock. On pressure it 
disappears at this point to reappear on the outside and just behind 
the hock. If pressed to the front from the outside it will then appear 
on the inside of the hock. On its outer surface it presents a vein 
which is quite prominent, running from below upward, and it is to 
the preternatural dilatation of this blood vessel that the term blood 
spavin is applied. 
The thoroughpin is found at the back and on the top of the hock 
in that part known as the “hollows,” immediately behind the shank 
bone. It is round and smooth, but not so regularly formed as the 
bog spavin, and is most apparent when viewed from behind. The 
swelling is usually on both sides and a little in front of the so-called 
hamstring, but may be more noticeable on the inside or on the 
outside. 
In their general characteristics bog spavins and thoroughpins are 
similar to windgalls, and one description of the origin, symptoms, 
pathological changes, and treatment will serve for all equally, except 
that it is possible for a bog spavin to cause lameness, and thus to 
involve a verdict of unsoundness in the patient, a circumstance which 
will, of course, justify its classification by itself as a severer form of 
a single type of disease. 
We have already referred to the subject of treatment and the 
means employed—rest, of course—with liniments, blisters, etc., and 
what we esteem as the most active and beneficial of any, early, deep, 
and well-performed cauterization. There are, besides, commenda- 
tory reports of a form of treatment by the application of pressure 
pads and peculiar bandages upon the hocks, and it is asserted that 
the removal of the tumors has been effected by their use. Our 
experience with this apparatus, however, has not been accompanied 
with such favorable results as would justify our indorsement of 
the flattering representations which have sometimes appeared in its 
behalf. 
OPEN JOINTS, BROKEN KNEES, SYNOVITIS, AND ARTHRITIS. 
The close relationship which exists among these several affections, 
their apparently possible connection as successive developments of a 
similar, if not an essentially identical, origin, together with the 
advantage gained by avoiding frequent repetitions in the details 
