104 PRACTICE OF EQUINE MEDICINE. 



IV. CONSTITUTIONAL DISEASES. 



PURPURA HEMORRHAGICA. 



Name the synonyms. 



Purpura, petechial fever of horses, dropsy, anasarca, morbus 

 maculosus, scarlatina. 



Define Purpura. 



This is a constitutional disease, having its origin in the blood 

 and capillaries, and characterized by petechial spots on the mucous 

 membranes, and by swellings under the skin, the result of sanguine- 

 ous effusion. 



What is the pathology? 



Extravasations of the blood from the vessels are found in the 

 interstices of the various organs, as the lungs, spleen, kidneys, and 

 the subcutaneous tissue; there is a jelly-like mass, and the blood is 

 darker than normal and more fluid. 



Similar conditions exist on the skin and mucous membranes, 

 associated with hemorrhage on the free surface. 



Give the aetiology of this affection. 



It may occur as a primary disease, but is seen mostly as a 

 secondary condition. 



The real cause is not well understood, and, although probably 

 due to bacteria, producing toxins, one fact is obvious — that it 

 follows debilitating conditions, as influenza, strangles, pharyngitis, 

 intestinal catarrh, suppurative lymphangitis, pneumonia, pleurisy. 

 Many cases, however, make their appearance without previous 

 sickness. 



The variety of bacteria found are many and varied so that 

 no positive conclusion has as yet been drawn. 



Embolism and thrombosis are said to be causes; also, a dis- 

 ordered condition of the vasomotor system. Bad drainage, dark, 

 damp stables, poorly ventilated, seem to favor its development. 



What are the symptoms? 



In primary cases the symptoms come on suddenly; there is 

 an impaired appetite, possibly a tendency to diarrhoea, some fever, 

 and the animal dull and has somewhat of a stiffened gait. 



