CONTAGIOUS PNEUMONIA. 1 87 



In comparing contagious pneumonia and the abdominal form of in- 

 fluenza from the point of view of the subtlety of infection and rapidity 

 of extension marked differences, however, are apparent. As Fried- 

 berger and Frohner remark, the diffusion of the specific agent is 

 usually slower in the former case, and its method of propagation 

 different. Although in certain outbreaks among army horses con- 

 tagious pneumonia affected ten, twenty, or thirty subjects within a 

 few days, the occurrence is exxeptional ; whilst in the same period the 

 abdominal form of influenza might have attacked hundreds of animals. 

 Another difference noted by the same authors, confirmed by many 

 practitioners, and again recently mentioned by M. Laporte, has 

 reference to the mode in which the infection spreads. Contagious 

 pneumonia attacks irregularly, often affecting animals far removed 

 from the first case, while influenza is more frequently transmitted 

 from one case to another, following a fairly regular line. 



Direct transmission is the rarest method of contagion. The disease 

 is generally spread bj- intermediate channels, such as the air, forage, 

 manure, pails, or mangers, or even by attendants, grooms, owners, or 

 veterinary surgeons. In one instance the disease was communicated 

 to a mare, isolated far from the infected stable in a special place, by 

 means of a mash taken from the manger of a horse suffering from 

 pneumonia. In order to prevent it being "wasted" the groom had 

 given this mare the bran left by the patient. 



Many veterinary surgeons have seen enzootics of contagious pneu- 

 monia in stables without infection having been introduced by recently 

 bought animals, and in towns or parts of the country where the disease 

 did not previously exist. In these cases the locality and especially the 

 soil have been blamed. In all probability the infectious organisms 

 had been in existence, but had long remained dormant or continued 

 growing as saprophytes, and afterwards, under the influence of un- 

 determined conditions, recovered their virulence and primar}- activity, 

 causing an outbreak of disease. 



The contagious material enters by the respiratory passages sus- 

 pended in the inspired air, or by the digestive mucous membrane along 

 with food or drink. Schiitz declared the specific agent to consist of 

 a little ovoid bacterium generally arranged in twos, the biological 

 characters of which he described. Though pathogenic in the horse^ 

 rabbit, guinea-pig, mouse, and pigeon, it is without action on the pig 

 and fowl. Inoculation of a culture of this microbe into the horse 

 reproduces the disease. If introduced into the parenchyma of the lung 

 by transfixing the wall of the chest and the pleura with an antiseptic 

 needle or trocar, the symptoms of contagious pneumonia appeared in 



