may enter the body through the uninjured mucous membranes of the
respiratory tract and genital organs, or through wounds of the skin.

_The period of incubation_ may be from a few to many days.

_The symptoms_ may be _acute_ or _chronic_ in nature. The _acute form_
pursues a rapid course. It is frequently seen in mules and asses, and it
may develop from the subacute or chronic form in horses. When the disease
is acute, the animal has a fever, is stupid, does not eat, and may have a
diarrhoea. In this form the lymphatic glands suppurate, the animal loses
flesh rapidly and dies in from one to two weeks.

[Illustration: FIG. 115.--Nasal septum showing nodules and ulcers.]

The _chronic form_ is the most common. It develops slowly and lasts for
years. The early symptoms of the disease (chilling and fever) usually
escape notice. The first visible symptom is a nasal discharge of a dirty
white color from one or both nostrils. This is usually scanty at first, and
intermittent, but later becomes quite abundant. The discharge is very
sticky, and adheres to the hair and skin. The most frequent seat of the
disease is in the respiratory organs, lymph glands and skin. Nodules and
ulcers appear on the nasal mucous membrane (Fig. 115), but they may be so
high up as to escape notice. The ulcers are very characteristic of the
disease. They are angry looking, with ragged, raised margins, and when they
heal leave a puckered scar. The submaxillary glands may be enlarged, and at
first more or less hard and painful, but later they become nodular and
adhere to the jaw or skin. Nodules and ulcers may form on the skin over the
inferior wall of the abdomen and the inside of the hind limbs and are known
as "farcy buds." Lymphatic vessels near these buds become swollen and hard.
The animal loses flesh rapidly, does not withstand hard work, and the limbs