Acute Fibrinous Pneumonia. Pneumonitis in the Hqrse. 253 



inflammation of these tissues and nuclei, with exudation usually 

 of a fibrinous material into their substance. 



Predisposing Causes, i. Age. A very eariy age is nearly 

 exempt, and from six years upward there are fewer cases relative 

 to the equine population, variations that may be better accounted 

 for by stabling, training and acquired immunity than by the mere 

 fact of age. Of 237 cases, 2 were 3j^ years ; 32 were 4 years ; 

 19 were 5 years ; 131 were 6 to 11 years ; 46 were over 11 years; 

 and 7 of uncertain age (Trasbot). 2. Sex. No visible effect. 

 3. Stabling, training, change of food. While the young colt 

 at pasture is practically immune, the period of stabling, transi- 

 tion to a dry and grain diet, and to the nervous excitement at- 

 tendant on training and unwonted work as shown in the statistics 

 of Percivall and Trasbot determine an enormous increase of cases. 

 In a cavalry regiment, Percivall found that 56.6 per cent, of all 

 lung diseases occurred before the fifth year, and Trasbot found 

 that at the Alfort Veterinary College 13.5 per cent, of all equine 

 pneumonias occurred in the fourth year. 4. Hot Stables. Im- 

 pure Air. These two conditions usually co-exist and prove 

 potent causes, especially in young horses brought from the fields. 

 We cannot, however, separate this cause as usually observed 

 from the action of pathogenic germs which are preserved and 

 concentrated in such places. 5. Poor Health. Debilitating 

 diseases, insufficient and poor diet, overwork, exposure to cold 

 draughts or darkness and any other cause which lowers the 

 vitality predisposes. 6. A Previous Attack. This usually 

 leaves some structural or functional change which renders the 

 lung more susceptible to a subsequent invasion. Against this 

 must be placed the immunity which follows the contagious forms, 

 but as this is usually exhausted in the course of six months it 

 does not invalidate the position that the permanent impairment 

 of pulmonary integrity is a predisposing cause. 7. Plethora. 

 Tending as this does to congestion it must be accepted also for 

 the next pathological step — pneumonia. 8. Climate and Sea- 

 son. This is notoriously an important factor. At Paris, Trasbot 

 met with 237 cases in the nine months from October to June in- 

 clusive, and but eight cases in the summer months — July, August 

 and September. In Great Britain, where the vicissitudes are 

 less severe, Percivall had in the cavalry horses in the seven 



