Symptoms Course. Treatment. 727 



eased side being lield lower (see figs. 104 and 105), but the lower 

 part of the head is generally turned back towards the sound 

 side. This turning of the head may be slight or 45° to 75° ; but 

 in birds it may be as much as 180° or more, so that the roof of 

 the cranium is in many cases in contact with the ground (see 

 fig. 105). Rolling movements are common in the small animals, 

 but quite exceptional in the large, the rolling always being to- 

 wards the diseased side. Animals sometimes take up strained 

 positions. The abnormal position of the head causes the ani- 

 mals, if they try to move at all, to walk in circles towards the 

 sound side, but sometimes the movements are in the opposite 

 direction or at any rate they cannot walk in a straight line. 

 There is frequently horizontal nystagmus towards the sound 



Fig. 105. Paralysis of tlie vestibular nerve in ^ fowl. Twisting of the head 

 more than 180^.' 



side with conjugate position of the eyes (see page 593). There 

 may be difficulty in taking food and in birds it is commonly 

 quite impossible. 



If the disease is bilateral it closely resembles cerebellar 

 ataxia, only the symptoms are limited to the head and neck. 



Course. While paralysis due to injury generally disap- 

 pears completely within a few days to a week, other diseases of 

 the auditory nerve are, as a rule, persistent, depending upon 

 the nature of the primary disease. 



Treatment. In traumatic cases quiet, and artificial feeding 

 if necessary, are sufficient. If there is coincident disease of 



