DISEASES OF THE LUNGS. 159 



than in croupous pneumonia, and is sometimes so much 

 prolonged that thickening of the bronchi and alveolar walls 

 remain. 



3. PATHOLOGICAL CHANGES IN INTERSTITIAL OR 

 CHRONIC PNEUMONIA— This form, like all other chronic 

 inflammations, is characterized by gradual increase in the 

 connective-tissues of the organs, leading to induration of 

 the textures and obliteration of the alveolar cavities. It is 

 often associated with catarrh and dilatation of the bronchi, 

 and sometimes with ulceration of the bronchial walls. 



The thickening of the connective-tissue has been observed 

 in the pneumonia of glanders, in which the exuded materials 

 break down into a thin purulent fluid. 



SYMPTOMS AND COURSE OF PNEUMONIA— Inflam- 

 mation of the lungs in the horse is mostly associated with 

 bronchitis and pleurisy, though uncomplicated cases of true 

 acute pneumonia do sometimes occur. 



In many instances, the first manifestation of this disease 

 is the catarrh which accompanies or precedes the inflamma- 

 tion of the lungs. Pneumonia is sometimes ushered in with 

 a severe rigor, succeeded by a hot stage. The pulse is 

 accelerated but very variable, and numbers usually from 

 90 to 100 beats per minute. The artery is hard and full at 

 the outset, or it may be soft and full. In some instances it 

 is irregular, intermittent, or dicrotic. 



The temperature is raised and may read from 103° F. 

 to as high as 106^ The skin and extremities are cold, 

 and the visible mucous membranes are red and injected. 

 The bowels are constipated, and the f?eces coated with 

 mucus. 



The horse loses his appetite, and wanders to and fro in 

 his box in a dull, dejected manner, showing no inclination 

 to lie down. 



If the case be complicated with pleurisy, the breathing 



