ANATOMICAL CHARACTERS. 281 



colour, iind of greater friability tlian in health. Most pro- 

 bably all these changes are the direct result of structural 

 alteration, closely related to eliusion of fluid material into the 

 intimate texture of both cortical and medullary portions ; the 

 lymph-spaces, or alveoH, are certainly distended, and the 

 trabecula3 stretched and less resistant. 



Both the liver and spleen are somewhat texturally altered. 

 This alteration, however, is not of a constant or uniform cha- 

 racter, either in the organs themselves and individually, nor as 

 to the relative extent to which they are severally affected. 



Sometimes the liver is simply congested ; at others there is 

 obvious want of colour and great friabihty. When this organ 

 is comparatively little involved the spleen will most probably 

 show greater changes ; these are chiefly in connection with the 

 composition and character of the blood which it contains, and 

 the relative amount as compared with its normal condition. 

 The lungs, besides the petechial markings which may exist on 

 their pleural surfaces, are congested and engorged with blood, 

 presenting the same general characters as are exhibited by it 

 in other situations and tissues of the body, while there is often, 

 in the smaller bronchi, a quantity of rusty coloured spume. 



It is certainly not always the case that the whole of these 

 morbid appearances are presented equally well developed in all 

 fatal cases of purpura. The ordinary forms are those where 

 the lesions and peculiar vascular changes are more distinctly 

 marked and of a dominant character in one organ or region 

 of the body, being much less distinctive elsewhere. It is per- 

 fectly possible that a fatal result may occur with little or no 

 extravasation apart from the petechial markings on certain 

 mucous and serous membranes. 



Symptoms. — Although purpura hiemorrhagica in the horse 

 does show itself as an idiopathic affection unassociated with 

 other diseased conditions, it is yet most frequently encoun- 

 tered, as we have already said, as the result or sequel of some 

 other affection, particularly of the air-passages and organs of 

 respiration. 



When associated with such diseases as catarrh, strangles, 

 or influenza, it is not found developing during the height of 

 the febrile symptoms, nor even at the period of defervescence ; 

 it is usually when the condition of convalescence has been so 



