_Circumscribed suppuration_ or _abscess_ is infrequent though occasionally met with in the horse and ox. In this case the excessive exudation at one point liquefies and the surrounding lymph becoming organized into a vascular membrane an abscess is formed. This may burst into the bronchial tubes and be discharged by the nose. In less favorable cases it makes its way toward the pleural surface and opens into the cavity of the chest. It is impossible to detect the existence of a pulmonary abscess though after it has burst into a bronchial tube the existence of the cavity may be ascertained by the amphoric sound heard on auscultation. Animals may recover from such pulmonary suppurations or if they are too extensive the consequent depletion may induce hectic and death. =Gangrene= of the lung is happily rare and has appeared to be connected with close, foul stables, previous ill-health, and work after the onset of pneumonia. It is characterized by high temperature (106° to 108° F.) by great dulness and prostration due to the poisoning of the nerve centres, by weakness and unsteadiness, by complete loss of appetite, and at length an intolerable fœtor of the breath as if from putrefying animal matter. In rare cases recovery may take place, the dead portion having become detached and expectorated. =Consolidation= from =hepatization= is the condition in which the inflamed lung is always found, in the second stage of the disease. The lung has then the density and brownish red appearance naturally belonging to the liver (_red hepatization_), which changes on the occurrence of softening of the exuded products to a grayish hue (_gray hepatization_). But after the subsidence of the acute symptoms, the process of liquefaction and absorption is not always complete, a portion of the exuded product becomes vascular, is developed into fibrous tissue and remains permanently impervious to air. Such is the state of the lung in many cases of _thick_ or _short wind_ in horses when these have occurred as a sequel of pneumonia. A horse suffering in this way has the breathing habitually accelerated and is thrown into a state of great distress by any attempt to make him perform hard work such as galloping, dragging a load up hill and the like. A _chronic cough_ may equally accompany this condition. =Pathological Lesions.= These differ according to the stage of the disease. In the _first stage_, that of congestion the lung tissue is engorged with blood as described under the head of =congested lungs=. As early as 6 or 7 hours after artificial irritation, the alveoli of the affected part are already filled by exudation and cell proliferation. Until this has taken place the alveoli can still be distended by blowing into the bronchial tube.