Hepatisation only occurs some days afterwards, and with it irregular partial dulness localised in the lower zones, disappearance of the respiratory murmur in the corresponding regions, exaggeration in the infected regions, an expiratory sound which is barely perceptible or may be of a blowing character, or, again, after several days may be transformed into a tubal souffle.
The cough then becomes frequent, generally difficult, paroxysmal, feeble, and easily provoked. The appetite suffers, the patients seem to prefer fluid nourishment and lose flesh very rapidly.
If the broncho-pneumonia is about to terminate in suppuration or gangrene, the respiration becomes sighing, the breath fœtid, and the cough is accompanied by a greyish muco-purulent or gangrenous discharge.
When the abscesses are deep-seated, the alarming symptoms retain their primary degree of intensity for weeks, until the animals are completely exhausted. Abscesses, originating in deep-seated parts, may even extend towards the surface of the lung, and produce either adhesive pleurisy that can be detected by palpation, or exudative pleurisy, easily recognised on percussion.
When the infective microbes are not pyogenic the general condition appears less grave, the animals exhibit only moderate fever, appetite is diminished but not lost, wasting is slower, and may continue for months, but the affected portions of lung become converted into fibrous masses or a material resembling spleen pulp.
The duration of infectious broncho-pneumonia, therefore, varies with the nature of the infecting organism. In cases which terminate in gangrene, the animals may survive for three or four weeks; in those where suppuration occurs, for several months. In short, recovery is the rule in simple broncho-pneumonia; but from an economic standpoint there is little reason for keeping the animals alive.
Diagnosis. The diagnosis is not generally very difficult; for if at first the case may be mistaken for one of simple pneumonia, the persistence or prolonged aggravation of the symptoms and the irregularity in position of the lesions revealed by percussion and auscultation enable the condition to be distinguished at an early period from simple pneumonia.
Confusion with acute or chronic pleuro-pneumonia may easily be avoided by noting the absence of pleural effusion, and of the soft pleuritic souffle of peripneumonia, etc.
Where auscultation is chiefly relied upon it is more difficult to differentiate between this disease and acute tuberculosis, and between it and broncho-pneumonia produced by foreign bodies, although the latter disease develops differently.
Prognosis. The prognosis is always extremely grave and, in cases where there is gangrene or abscess formation, fatal. From the economic standpoint the chronic form is also very grave.