PREVENTIVE MEDICINE 285 



of the disease at later periods. Animals may thus pass through 

 several attacks but after the first these are often milder and tend 

 to assume the atypical (catarrhal fever) form. Attempts have 

 been made to vaccinate animals by the use of both living and dead 

 cultures applied subcutaneously and intravenously. Serum from 

 hyperimmunised animals has been used both as a prophylactic and 

 curative agent. Opinions vary considerably as to the efficacy of 

 these measures. It seems that large doses of a good serum injected 

 intravenously may be beneficial in the treatment of the more 

 malignant (cutaneous, &c.) forms of the disease. 



PURPURA HLEMORRHAGICA. 



Purpura (petechial fever) is a low fever associated with the 

 formation of multiple larger or smaller haemorrhagic centres in 

 the skin and subcutaneous tissues, in the respiratory and alimentary 

 mucous membrane as well as in other organs. Though usually 

 described as a microbial disease no causal organism has been demon- 

 strated, nor can the disease be produced experimentally. Purpura 

 is generally regarded as a secondary disease, as following upon or 

 associated with any disease or condition which lowers the vitality 

 of the animal. Some even doubt that it occurs as a primary disease, 

 but with the author at least no such doubt exists ; at any rate it may 

 and frequently does manifest itself as the primary indication that 

 the animal is ill. Though generally considered to be associated 

 either with a debilitating disease or with an unhygienic environ- 

 ment or a combination of both, purpura may appear when these 

 conditions are absent. Nevertheless, this disease is to be regarded 

 as one which comes within the scope of the hygienist. The author 

 has seen it occur as a " primary " disease in a single horse stable, 

 if such it could be called, that abutted on a particularly offensive 

 earth closet while, on the other hand, purpura fails to become evident 

 under other conditions no less conducive. Thus, on a transport 

 plying between the United States and South Africa during the 

 South African War in which in four voyages 4369 horses were 

 carried under conditions which would not have passed muster in 

 the late war, not more than 6 or 8 cases were observed. As a rule 

 cases are isolated, and though some hold that the disease is 

 infectious and that it may pass from one animal to another in the 

 same stable there does not seem to be any definite evidence that 

 this is so. If such were the case one might have expected that 

 under transport conditions, such as those with which we have been 

 associated, the disease would have shown a tendency to spread 



