372' Diseases of Sheep, 



used to attend the sheep, and where they frequent the pas- 



tiu-es. 



The bladder consists of a thin membrane, filled with 

 watery, yellowish fluid, in which a large number of small, 

 white bodies are floating, each the immature tapeworm, 

 provided with hooks and a sucking mouth, which it applies to 

 the inner walls of the bladder, and through them derives its 

 nourishment from the brain substance. 



Symptoms. — These are curious and well marked. AYhen 

 the animal is first affected there are staggering, reeling and 

 stupefaction, little appetite and debility. In walking the 

 animal describes a circle, always turning in the same 

 direction, lifting its feet high, and often running against ob- 

 stacles. Total blindness and deafness may ensue. These 

 may subside for a while, as the contents of the skull adapt 

 themselves to the hydatid ; but as it continues to enlarge and 

 consume the brain, the symptoms return with greater sever- 

 ity, palsy creeps on, the animal can no longer stand, becomes 

 insensible and dies. 



The location of the hydatid in the brain is indicated by 

 the motion or turning of the sheep. If it is in the left lobe 

 or half of the brain the animal turns to the right ; if in the 

 right lobe, his turning is to the left ; if in the back part of 

 the brain, the cerebellum, the movements are performed 

 without control, the head is elevated, the limbs moved with 

 difficulty, and he starts and falls repeatedly ; finally, if the 

 hydatid is in the middle of the brain in front, the sheep goes 

 forward in a straight line, holds its nose in the air, steps very 

 high, and soon loses the sight of one or both eyes. 



The growth of the hydatid is rather rapid, and in three 

 weeks' time from the first appearance of the symptoms, if 

 the skull be pressed firmly with the thumb where the above 

 rules point out the lodging of the hydatid, a noticeable de- 

 gree of softening will be found, as if the skull were want- 



