VETERINARY OPHTHALMOLOGY. 119 



horse to swerve. And here a word. In making these 

 feints, be sure you do not cause a current of air to 

 strike the animal which would cause him to start and 

 so possibly deceive. The ears are held erect and move 

 quickly on appreciating any sound. He will also step 

 high. 



Treatment is useful only when the disease. is symp- 

 tomatic of some removable cause. Should the condi- 

 tion persist after the subsidence of the supposed cause, 

 try blister, (post auricular,) and give 3 ss doses of 

 nux vomica daily. 



Atrophy of the Optic Nerve. This may be the oc- 

 casion of the condition above described and (fig 64) 

 is to be watched for, especially on passing horses. So it 

 is imperative to know and handle the ophthalmoscope 

 intelligently. The general symptoms are as described 

 under Amaurosis. Tlie ophthalmoscopic symptoms are 

 here the interesting ones. The disk is almost always 

 white — decidedly so — but may be grayish, and the 

 lamina cribrosa may be distinguished. The blood sup- 

 ply is lessened, witli consequent paleness, and the larger 

 vessels will be lessened in caliber. Thus is it very evident 

 that the student must /oioto the appearance of a normal 

 fundus. (See colored plate.) Colored crayons and a 

 blackboard will not convey the required picture, be 

 they ever so happily depicted. 



The disk will be sharply outlined, and often this 

 outline will be pigmented. If this atrophic condition 



