symptom, and we should not place too much emphasis on it. If the lungs
become tubercular the animal usually has a slight, harsh cough. The cough
is first noticed when the cattle get up after lying down, when the stable
is first opened in the morning and when the animals are driven. If the
chest walls are thin, soreness from pressure on the ribs may be noted. By
applying the ear to the chest wall and listening to the lung sounds,
absence of respiratory murmurs and abnormal sounds may be distinguished,
due to consolidation of the lung tissue, abscess cavities and pleural
adhesions. In a well-advanced case the hair is rough, the skin becomes
tight and the neck thin and lean. The animal may breathe through the mouth
when it is exercised. Weakness may be a prominent symptom.

[Illustration: FIG. 90.--Tubercular spleens.]

Breeding animals that are well fed and cared for may live for several years
before showing noticeable symptoms of tuberculosis. The disease progresses
more rapidly in milch cows, especially if given poor care. Calves allowed
to nurse a tubercular mother that is giving off tubercle bacilli frequently
develop enlarged throat glands and the intestinal form of the disease.

Hogs develop a generalized form of tuberculosis more quickly than cattle,
but an unthrifty, emaciated condition is seldom noted in hogs under ten
months old.

POST-MORTEM LESIONS.--The effect of the tubercle bacillus on the body is to
irritate and destroy the tissues. Lumps or tubercles form in the lymphatic
glands, liver, lungs, spleen (Fig. 90), serous membranes, kidneys and other
body organs (Figs. 91 and 92). The tubercles may be very small at first,
but as the disease progresses they continue to enlarge until finally a
tubercular mass the size of a base-ball, or larger, is formed (Figs. 93,