DISEASES OF THE NERVOUS SYSTEM. 233 



What are the causes ? 



The active form is seen among young and plethoric animals 

 which are predisposed. Heat exposure with hard work; animals 

 kept in dark stables and suddenly exposed to light; certain drugs, 

 as opium. Also the action of ptomaines and toxins. 



The passive form may be caused by cardiac diseases, lung dis- 

 eases, blood diseases. Tight collars, etc., preventing the return 

 flow of blood from the brain. 



What is the morbid anatomy? 



The brain substance, as well as the meninges, are congested 

 in pronounced cases. The color varies according to whether the 

 active or the passive form exists; in the former a bright red color 

 is present, while in the latter it varies from a blue to a purple. 



Give the symptoms of cerebral congestion. 



The symptoms are not well defined and are not constant. 



How is the diagnosis made ? 



The cases are rare in the horse, and when they occur they are 

 apt to be overlooked, as they are difficult to make out on account 

 of the symptoms being vague. 



What is the prognosis? 



Good, unless rupture of the blood-vessels occur or it be asso- 

 ciated with organic disease, especially of the heart. 



What are the indications for treatment ? 



Keep the animal quiet in a box-stall with good ventilation 

 (cool air). 



Act on the bowels to draw the blood from the brain. Assist 

 the purge (if necessary) by enemas (stimulating). 



Locally, cold applications to the head. Some of the drugs 

 indicated are belladonna, hyoscyamus, potassium bromide, aconite, 

 ergot. 



CEEEBEAL ANEMIA. 



Give the synonym. 



Anaemia of the brain. 



What is cerebral anaemia? 



It may be defined to be a lessened amount of blood in the 

 cranial contents. 



