spiration breaks out
at intervals on various parts of the body. If with this we get a puffy and
tender swelling in the hollow of the heel, our diagnosis may be certain at
any rate as to the existence of joint trouble, although, from reasons we
have given, we may not be able to mark its exact nature.

2. _Chronic_.--Simple synovitis may in many instances become chronic. In
this case we have simply a pouring into the synovial capsule of serous
fluid, and with it an increased quantity of synovia--this time with an
absence of the usual inflammatory phenomena. Beyond the swelling of the
capsule there is little to be noticed. The joint becomes perhaps a little
weaker, but pain or tenderness and heat are entirely absent. Such a
condition, by reason of the natural rigidity of the parts, is not to be
observed in the foot, although at times it must most certainly occur.
Examples of such a condition are to be found in bog-spavin, in hygroma of
the stifle, and sometimes in the fetlock. From a study of these, we know
that they may be induced by frequent attacks of acute synovitis, from
repeated slight injuries or bruises, or from strains to the ligaments of
the joint; or that they may be chronic from the outset. We know, too, that
in such cases the synovial membrane becomes thickened, and that in places
it may have extended somewhat over the edges of the articular cartilages.
It is only fair to suppose that such changes occur also in the pedal
articulation. In that case we may take it for certain that the natural
rigidity of the surrounding structures has the effect of pushing the
thickened membrane further between the bones of the joint than occurs in a
like condition elsewhere, leading, of course, to a lameness that is marked
in degree but occult as to cause.

In our minds there is no doubt that many of the occult and chronic forms of
foot-lameness we meet with in practice are in this way to be accounted for.
We may, in fact, explain them by suggesting either a chronic synovitis
alone, or a synovitis complicated with periostitis.

_Treatment of Synovitis_.--If a joint has been injured, as we have
suggested, by slight blows or other causes--in other words, if the injury
is subcutaneous, and no wound is in existence--then there is no treatment
which offers better results than does the continued application of cold.

At the same time, the animal should be slung, or, if non-excitable and
inclined to rest, allowed at intervals to lie