142 Veterinary Medicine. 



tissue, to form hot, tender, nodular, diffused, or general swell- 

 ings. 



Causes. The causes of petechial fever are not clearly made 

 out. Bacteria are found in the early exudate, but these are not 

 constant in kind and it is not unreasonable to suspect that these 

 may be results rather than causes of the lesions. On the other 

 hand there may be an as yet undiscovered organism present, the 

 products of which are capable of producing the disorder. Or the 

 latter may be due to a combination of the toxins of two or more. 

 Among the bacteria found may be named : The pus microbes, 

 cocci, streptococci, staphylococci, and bacilli, have been found and 

 adduced as causes, also diplococci, the bacillus hsemorrhagicus of 

 Kolb, the streptococcus of strangles, the microorganism of con- 

 tagious pneumonia and that of influenza, with a variety of others 

 too great and too inconstant to be accepted as proof of cause. 

 The fact that rarely more than one animal suffers in the same 

 stable at the same time might be held to oppose the idea of con- 

 tagion and of a definite organized germ. 



Hence the theory of its causation by the presence in the system 

 of the toxic products of bacteria rather than the bacteria them- 

 selves. (Dieckerhoff. ) Cadeac supposes that any toxin which 

 causes capillary dilatation may determine the disease, and calls 

 attention to the fact that the injection of mallein (a vaso-dilator) 

 aggravates the phenomena of petechial fever and determines 

 enormous local exudations and engorgements. He notes further 

 the potent vaso-dilator action of the products of strangles, conta- 

 gious pneumonia, and influenza which are among the most fre- 

 quent antecedents of petechial fever. Dieckerhoff also looks on the 

 phenomena as the result of poisoning by the absorbed toxins of 

 the microbes of suppuration, which modify the nutritive changes 

 in the walls of the capillaries and determine exudations and 

 haemorrhages. Zschokke thinks that there is infection of the 

 intima of the capillaries, with the formation of coagula. Clots 

 are not found, however, apart from haemorrhages. 



The toxin theory receives indirect support from the absence of 

 the same specific lesions in simple mechanical congestion of the 

 capillaries and veins. Ranvier had no such results from tying 

 the veins of a rabbit's ear. Roger tied the auricular veins of the 

 rabbit, and then cut the sensory nerves without effect : he then 



