240 PRACTICE OF EQUINE MEDICINE. 



ACQUIRED HYDROCEPHALUS. 



Give the synonyms. 



Immobility; chronic hydrocephalus; the animal is called a 

 dummy. 



Define this form. 



It is a chronic disease of the brain, with an accumulation of 

 fluid in the ventricles and characterized by an alteration of con- 

 sciousness, conception, and sensibility of varying degree. 



Give the causes of this affection. 



There is a hereditary tendency, and thus the animal should 

 not be bred; in these cases, common-bred animals — especially 

 those narrow between the ears and eyes — are the ones principally 

 predisposed. 



It may follow congestion or inflammation of the brain; also 

 tumors causing pressure. Poor food, bad hygienic surroundings, 

 hot weather, bad-fitting harness, overwork, etc., are among the 

 causes. 



What is the pathological anatomy? 



The convolutions of the brain are flattened, the depressions 

 ot sulci less marked or obliterated, the cortical substance dimin- 

 ished and pale, corpora quadrigemina, the optic thalami, etc., flat- 

 tened from pressure of the exudation, the ventricles contain fluid, 

 the membrane forming the walls of the ventricles is thickened. 

 Continued pressure of the exudate causes an atrophy of various 

 portions of the brain, thus interfering with their functions. 



What are the symptoms ? 



The symptoms have to be studied under two conditions: first, 

 when at rest in the stall, and, second, when the animal is in motion. 



When in the stall there is a disorder of consciousness, 

 shown by the peculiar position the animal assumes by standing 

 diagonally in the stall, the head hanging down or supported on 

 the manger, eyes half closed, legs crossed, resting the heel of the 

 shoe on the coronet of the opposite foot, sensibility is diminished, 

 the animal taking no notice of the whip or flies. In drinking, they 

 plunge their heads to the bottom of the trough, drink a little, 

 and then stop; soon the nose is withdrawn in order to get breath. 



