PURPURA. 501 



products of the previous inflammation becoming broken up. The 

 waste matter with which the blood is loaded, irritates the kidneys 

 and gives rise to the profuse staling. 



Purpura Haemorrhagica {Petechial Fever). 



This appears to be a grave alteration of the blood due to the 

 introduction into the system of virulent material produced under 

 bad sanitary conditions, or generated within the body during 

 previous illness ; or it may be caused by constitutional taint or 

 weakness. As a rule, it follows some debilitating disease, such as 

 strangles, influenza, or catarrh ; in which cases, it appears during 

 the stage of convalescence. It is not infectious, it" cannot be 

 communicated by inoculation, and no characteristic microbe has 

 been found in horses suffering from it. Up to the present, rothing 

 is known about its cause. It somewhat resembles the purpura 

 liaemorrhagica of man. 



NATURE OF THE DISEASE.— We may roughly say that the blood in 

 purpura, is in a more or less decomposed state. The amount of albumin in 

 it is greatly diminished ; the red corpuscles are more or less shrivelled and 

 broken up ; and the watery constituents show a marked tendency to 

 separate themselves, and, consequently, rapidly ooze through the walls of 

 the blood-vessels ; thus producing the characteristic swellings. Infiltration 

 of this fluid into the brain, in excessive quantity, causes insensibility ; and 

 into the lungs, suffocation. The fluid which thus escapes, holds in solution 

 a quantity of the colouring matter of the blood, which is obtained from the 

 broken-up red corpuscles, and which causes the various infiltrated tissues 

 to become stained : hence, the name purpura haemorrhagica. The blood 

 itself is darker than usual, owing to changes undergone by its colouring 

 matter. It also loses, to a marked extent, its property of coagulating. 



Whether the blood only is affected, or whether the walls of the vessels are 

 also implicated, are questions which our present state of knowledge does not 

 enable us to answer with certainty. 



VARIETIES OF PURPURA.^For practical purposes, we may 

 regard this disease as appearing under two forms, namely, severe 

 and mild, 



SYMPTOMS OF SEVERE PURPXIRA.^The most noticeable 

 flrst symptom is prominent swellings, whiqh appear suddenly, and, 

 usually, on the inside of the thighs, below the belly, sheath, breast, 

 and about the mouth and nostrils. The swellings are hard, hot 

 and painful to the touch, though not to a very marked degree. 

 Simultaneously with the swellings, or a few days before them, 

 blood-spots (petechise) of a purple or dark red colour make their 

 appearance on the various mucous membranes ; and on those 

 portions of the skin which are devoid of pigment. They usually 

 yary in size from that of a fle?i-bite to that of a shilling, or may be 



