HYDROCEPHALUS 65 



PERMANENT INTERNAL HYDROCEPHALUS 



The presence of fluid in abnormal and permanent 

 amount within the ventricles of the brain produces a 

 pathological state in the affected animal. This patho- 

 logical condition has been described by various writers 

 under such names as chronic internal hydrocephalus and 

 chronic dropsy of the ventricles. Among horsemen the 

 horse so affected is called a ' ' dummy. ' ' 



Permanent dropsy of the ventricles may follow any 

 acute disease of the brain and spinal cord, or their 

 meninges. In other instances it develops gradually as 

 the result of slowly progressing anatomical changes in the 

 region of the ventricles. In all cases the symptoms pro- 

 duced ensue from the effects of increased intra-cranial 

 pressure. 



Symptoms. The best description of the symptoms in 

 this condition is conveyed by the name which horsemen 

 have given it, namely, "dummy." Horses that are the 

 subjects of a permanent internal hydrocephalus appear 

 to possess only a fraction of normal alertness and vivac- 

 ity. The physiognomy at once betrays the low degree 

 of consciousness ; the expression is almost comparable to 

 that of idiocy. The horse performs a variety of abnor- 

 mal movements in connection with feeding, drinking and 

 other ordinary functions. Grotesque and odd positions 

 of the limbs are frequently assumed. The horse at times 

 leans against objects, rests the head on railings, posts 

 or mangers, appearing partly asleep in the act. While 

 eating, the animal frequently pauses, standing idiotically 

 for variable periods of time with a partly masticated 

 bolus of feed or hay held in the mouth. While drinking, 

 the horse frequently immerses the head to the eyes, sud- 

 denly and surprisedly jerking up the head as it finds the 

 water entering the nares. 



