uscular or purely a nervous
lesion, or a compound of both--it still continues, if an etiologist is
bound to possess universal knowledge within the scope of his special
studies, to be his reproach and his puzzle.

_Treatment._--When there is a known or suspected cause the treatment
should be directed toward this factor. If due to local inflammation of
the hock or foot, only this local lesion should be treated. If it
remains after the local lesion has healed, or if we have no assignable
cause, the best results have followed the sectioning of the lateral
extensor of the foot. A competent veterinarian alone should undertake
this operation.

THROMBOSIS.

There are certain forms of lameness which are very peculiar in their
manifestation, and which to the nonprofessional mind must appear to
belong to the domain of mystery or theory instead of occupying a
well-established position among the subjects of equine pathology. Yet
they are no less susceptible of actual demonstration and of positive
comprehension than many facts which, plain and familiar to the general
understanding now, were once ranked among things occult and
unsearchable. A thrombus, considered as a cause of lameness, may find a
place among these understood mysteries.

_Cause._--Under certain peculiar conditions of inflammation of the blood
vessels, and also in aneurisms, clots of blood are sometimes formed in
the arteries and find their way in the general circulation. At first,
while very small, or sufficiently so to pass from one vessel to another,
they move from a small vessel to a larger, and from that to one still
larger, constantly increasing in size until at some given point, from
their inability to enter smaller vessels, their movement is finally
arrested. The artery is thus effectually dammed, and the clot in a short
time cuts off completely the supply of blood from the parts beyond. This
is thrombosis, and it often gives rise to sudden and excessive lameness
of a very painful character.

_Symptoms._--Thrombi may form in any of the arteries, and doubtless have
been the cause of many cases of lameness which could never be accounted
for. If they exist in small arteries their diagnosis will probably fail
to be made out with certainty, but when situated in the larger trunks a
strong suspicion of their presence may be excited. In some cases they
may even be recognized with positive accuracy, as when the vessels which
supply the posterior extremities are