POLL EVIL. 463 
to the formation of an abscess. But the situation of the part is such that 
the matter cannot escape, even if the skin over the points of the bones is 
perforated, and it has a tendency, by the force of gravity, to burrow down 
among the muscles which connect the shoulder-blade with the trunk. 
The consequence is, that there is extensive inflammation, and often lame- 
ness of the shoulder, which could readily have been prevented by using 
proper care before the mischief was done, or removed by the adoption of 
suitable treatment afterwards before the disease is confirmed. 
The symptoms in the early stage (that is, before a fistula is established) 
are merely an enlargement of the ends of the spinous processes, accom- 
panied by heat and tenderness, but these go on until an abscess forms, 
which may be known to the touch by the fluctuating nature of the sensa- 
tion which it gives on pressure by the fingers of each hand. As soon as 
this is made out, an opening should be made as low down as possible on 
the right side, taking care that it will allow all the matter to run out as 
fast as it forms. The reason why the right side should be chosen is, that 
most horses lie down on that side ; but if the subject of fistulous withers 
is in the habit of lying on the left side, the opening should be made there 
in preference. When an actual fistula has been established, and the 
matter points before or behind the shoulder blade, a sufficiently large 
opening should at once be made, taking care again that there is no pouch 
below it which will permit any accumulation. It is better to divide even 
important muscles than to suffer this to exist. In recent cases the establish- 
ment of this dependent opening will alone suffice to effect a cure ; but 
in those of long standing the lining of the fistulous passage or passages 
has become converted into a substance almost resembling cartilage, 
and refuses to throw out healthy granulations, so as to lead to adhe- 
sion of its walls. Here a stimulus must be applied to their interior, which 
may be either mechanical, in the shape of a seton tape passed through 
from end to end and left there, or chemical, by means of injections. The 
latter are best composed of chloride of zinc (Sir W. Burnett’s disinfecting 
fluid), diluted with water. One drachm of this should be mixed in a pint 
of water, and carefully injected into every part of the sinus twice or thrice 
a week. 
POLL EVIL. 
Pott Evin is exactly similar in its nature to fistulous withers, being 
produced by a blow on the prominent ridge, which is situated on the top 
of the poll. The blow is generally produced in the stable, by the horse 
suddenly lifting his head and striking it against a low beam or the lintel 
of the door. Or it may be caused by frequently straining against the 
halter rein, and thus producing irritation and inflammation of the part. 
As the ligamentum colli is attached above, and anterior to, the inflamed 
part, when matter forms it is confined and gives intense pain; besides 
which, it is a long time before it opens a passage by natural means, The 
symptoms are a painful swelling on the poll, of a soft nature, accompanied 
by the sense of fluctuation on examination, just like that described as ac- 
companying fistulous withers. The treatment must be precisely similar to 
that described in the last section ; but as the matter when formed lies very 
close to the spinal cord, some caution must be exercised in adopting stimu- 
lating injections, which are apt to produce severe inflammation, likely to 
extend to these important structures. So also in opening it, the knife 
should not be carried deeply into the situation of the spinal marrow, which 
here lies exposed, and is easily divided (as in the operation known by the 
