844 DISEASES AFFECTING THE CEREBRAL CIRCULATION. 



paired or destroyed nutrition over a more or less extended area, 

 while the symptomsVhich might during life lead to the recog- 

 nition of these states are only such as point to peculiar 

 changes of a chronic nature in connection with brain-substance, 

 chiefly the condition known as softening. 



TV. Cerebral Hemorrhage — Apoplexy. 



Nature and Causation. — Intercranial ha3morrhage from rup- 

 ture of vessels of membranes or of brain-substance, usually 

 spoken of as apoplexy, 'from its most distinguishing and 

 diagnostic symptoms, sudden loss of consciousness, and dis- 

 turbance of motion and sensation — disorders which may at 

 the same time arise from other causes than haemorrhage, as 

 congestion or serous extravasation — is, apart from external 

 violence, rather rare in the horse. 



When unassociated with injury, it will be found to be 

 directly dependent on structural changes in the minute vessels 

 of the cerebral structure, or to changes in the brain-substance 

 acting upon the vascular canals, disturbing their usual re- 

 lation to surrounding textures, and so disposing to extra- 

 vasation. 



Anatomical Characters. — Neither in amount nor yet as to 

 exact situation is cerebral hemorrhage characterized by aught 

 like similarit}^ and upon the variations on these points in chief 

 depends the character of the symptoms. The principal situa- 

 tions in both idiopathic and traumatic haemorrhage are — 

 1. Into the substance of the brain ; 2. Within the ventricles ; 

 3. In connection with and between the membranes of the 

 brain. 



The first and the last are in the horse the most frequent of 

 occurrence, the internal haemorrhages occurring in cases where 

 the causes seem to reside in the brain, the meningeal in such 

 as result from violence. 



The appearance of extravasated blood is usually that of a 

 mass or clot, which, if recent, maintains its true blood-charac- 

 ters ; but when existing for some time is variously changed 

 both as to colour, consistence, and its relation to surrounding 

 textures. After some time it separates into fibrinous and 

 serous portions, undergoes gradual change of colour, may have 

 granular pigment or hivmatoidin crystals, and become encysted 



