Acute Croupous Pneumonia. Pneumonitis in the Horse. 223 



Death is fortunately the least frequent issue. It may follow on 

 rapidly advancing and general congestion of the lung, — asphyxia ; 

 from heart failure, the overworked organ becoming exhausted 

 under the strain of forcing the blood through the virtually imper- 

 vious lungs; from hyperthermia, the limit of bodily temperature 

 io8°F. having been reached or exceeded ; or from collapse and 

 exhaustion. 



In resolution which is the most favorable termination the fe- 

 brile and other symptoms subside and the exudations in the effused 

 lung undergo a process of liquefaction and absorption until neither 

 auscultation, nor percussion nor even the examination of the lung 

 after death will show the slightest trace of the pre-existent 

 disease. This is the most common termination in single pneu- 

 monia in the horse. 



Splenisation is that condition of lung already described under 

 the head of pul^nonary congestio7i, and if affecting both lungs 

 throughout, necessarily destroys life by arresting the aeration of 

 the blood. 



Abscess. Diffuse suppuration is very common in the stage of 

 gray hepatization. In this the affected lung becomes more or less 

 extensively infiltrated with pus limited by no distinct membrane 

 like the pus of an abscess, but exuding freely from the cut sur- 

 face of the lung or escaping from its interstices when it is pressed. 

 It is preceded and in its early stages associated with the formation 

 of granular masses and corpuscles. Its existence cannot be cer- 

 tainly ascertained though it may be surmised when after hepatiza- 

 tion of a portion of hxngo. in ueous rale, a sort of gurgling, is heard 

 in the adjacent bronchium and an abundant muco-purulent dis- 

 charge takes place from the nose. It threatens extensive destruc- 

 tion of lung tissue. 



Circurnscribed suppuration or abscess is infrequent though occa- 

 sionally met with in the horse and ox. In this case the excessive 

 exudation at one point liquefies and the surrounding lymph becom- 

 ing 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 impo.ssible 

 to detect the existence of a pulmonary abscess though after it has 

 burst into a bronchial tube the existence of the cavity may be as- 

 certained by the amphoric sound heard on auscultation. 



