The animals lose flesh, pant for breath when moved, drop to the rear of the flock, cough frequently, feed badly and end by becoming cachectic. Many suffer from the disease and yet remain in fair bodily condition.
On post-mortem examination the lungs are found not to collapse, having lost their elasticity, and are of a yellowish-white colour, which is only seen in this disease. On section the pulmonary tissue appears dense, hard, and of a fibrous and lardaceous character. At various points nodules with fibrous envelopes and caseous, yellowish or greenish contents are found.
When the caseous nodules are near the surface the pleura may be chronically inflamed and thickened. The liver and kidney frequently contain caseous lesions.
Diagnosis. The diagnosis becomes easy after the first post-mortem examination, for the lesions discovered cannot be mistaken for those of parasitic broncho-pneumonia, degenerated pulmonary echinococcosis or tuberculosis. In the living animal, on the contrary, the diagnosis is extremely difficult.
Prognosis. The prognosis is grave. No special method of treatment is known.
PULMONARY EMPHYSEMA.
Pulmonary emphysema, i.e., exaggerated dilatation of the pulmonary tissue by air, is not uncommon in the bovine species, and occurs under the two classical forms—(1) alveolar or intra-lobular emphysema limited to dilatation of the alveoli; and (2) interlobular emphysema, produced by the entrance and diffusion of air in the interlobular spaces in consequence of rupture of the lobules.
These two forms are very frequently associated:—
(1.) Emphysema by dilatation usually begins in the right pretracheal lobe; also in the cardiac and even in the posterior lobes.
(2.) Interlobular emphysema begins in the same regions, but it spreads readily in a backward direction, remaining interstitial; or, on the other hand, becoming subpleural at the periphery of the lung.