Equine Influenza. Adynamic Catarrhal Fever of SoKpeds. 16.5 



sou with the attendant fever and constitutional disturbance, 

 resembling in this respect, the lesions of contagious pneumonia. 

 It differs however in having a greater tendency to liquid infiltra- 

 tion of the connective tissue, and but for the lack of such tissues 

 in the horse's lung it would tend to approximate to the lesions of 

 the lung plague in cattle. It shows a distinct thickening of the 

 interlobular septa, a tendency to extension to the pleura, and 

 tO' issue in pleural and sub-pleural infiltration, and to a more 

 copious effusion into the pleural cavity than in either fibrinous or 

 contagious pneumonia. The lung tissue may be granular and 

 hepatized, but far more frequently it is only splenized, the lung 

 being the seat of a bloody infiltration, yet retaining much of its 

 elasticity and coherence. Portions may be infarcted and black 

 and large areas may have a pale or par-boiled appearance, and 

 gangrene is by no means uncommon. 



Diagnosis. This is based largely on the suddenness of the 

 attack, its epizootic character, the numbers attacked in rapid suc- 

 cession, and over a large area as contrasted with contagious 

 pneumonia, the sudden and extreme prostration and weakness, 

 the swelling, watering and discoloration of the eyes, the mildness 

 of the average case, the congestion of the upper air passages, and 

 in the mild cases a comparative immunity of the lungs, the irri- 

 tability or congestion of the gastro-intestinal mucosa, and the his- 

 tory of the case : — the arrival of the infected horses within a few 

 days from an infected place or coming through infected channels, 

 or the attack of new arrivals in a previously infected stable, or 

 the known advance of the disease towards the place where the 

 patients are, will usually serve to mark the true nature of the 

 affection. 



' As a help to correct diagnosis we give below some of the promi- 

 nent conditions and phenomena of the three forms of lung disease 

 known as fibrinous pneumonia, contagious pneumonia, and the 

 pneumonia of equine influenza : 



