_The specific cause of this disease_ is the _Bacillus bovisepticus_ (Fig.
101). This bacillus probably enters the body tissues by way of the lining
membrane of the intestinal and respiratory tracts. In the northern States,
cattle pasturing on marsh lands and swampy pastures are more often affected
with the disease in the late summer and fall than at other seasons of the
year.

The drinking of contaminated surface water that collects in muddy pools and
ponds may cause the disease. Cattle pasturing in stalk fields sometimes
become infected in this way. Dusty sleeping quarters and small, crowded,
muddy yards seem to favor the development of the disease in hogs. Exposure,
insufficient exercise and careless feeding are the predisposing factors.

[Illustration: FIG. 101.--_Bacillus bovisepticus_.]

_The symptoms_ vary according to the animal and organ, or organs of the
body affected and the violence of the attack. The disease may be acute or
subacute. The brain and its membranes, lungs and air-passages and
intestines may become affected. The symptoms may be classed under the head
of nervous, respiratory and intestinal (Fig. 102), and they may be very
unsatisfactory from the standpoint of diagnosis. The history and
post-mortem lesions are of most value in the recognition of this disease.
The local conditions, the loss of several animals in the herd and the
finding of hemorrhagic lesions in the different body tissues may enable
the examiner to correctly diagnose the disease. It is very advisable in
order to confirm the diagnosis to make a bacteriological examination of the
tissues.

The acute form of the disease is very fatal. Animals that have the subacute