depending on the nearness of the wound to a large nerve trunk or brain.

[Illustration: FIG. 110.--_Bacillus tetani_.]

The first _symptom_ observed is a stiffness of the muscles, especially
those nearest the point of inoculation or wound. The muscles of the head,
neck, back and loins are often affected first, and when pressed upon with
the fingers feel hard and rigid. The disease rapidly extends, producing
spasms of other muscles of the body. In breathing, the ribs show less
movement than normal, the head is held in one position and higher than
usual, the ears are stiff or pricked, the nostrils dilated, the lips rigid
or drawn back and the eyes retracted, causing the "third eyelid" to
protrude over a portion of the eye (Fig. 111). In most cases the muscles of
mastication and swallowing are affected. The animal may be unable to open
its mouth and swallows with difficulty. When standing, the limbs are spread
out so as to increase the base of support, and in acute cases about to
terminate fatally, the pulse is quick and small and the respiration
shallow, rapid and labored. The animal sweats profusely, falls down and
struggles violently, but remains conscious to the end.

[Illustration: FIG. 111.--Head of horse affected with tetanus, showing
"third eyelid" protruding over the eye.]

In the _subacute form_ (Fig. 112) the symptoms are mild, and the animal may
be able to move about, eat and drink without very great effort.

[Illustration: FIG. 112.--A subacute case of tetanus.]

_Treatment_ is largely preventive. All wounds should be carefully
disinfected. This is especially advisable in punctured wounds of the foot.