DISEASES OF HORSES AND CATTLE. 293 



It is also associated with derangement of the 

 nerves of the brain, and is said to be caused by 

 various vegetable and animal poisons. 



Symptoms: The eye looks glassy and is wider 

 open than natural, the pupil is dilated and gives 

 the animal a look of staring, the animal steps high 

 - and the ears are pricked up and it will run against 

 objects in its way. Williams says : "To detect the 

 paralyzed condition of the iris consequent upon the 

 loss of power in the optic nerve, all that the prac- 

 titioner has to do is to place the animal in a strong 

 light. If the pupil remains round and large, al- 

 though the eye presents no sign of organic change, 

 amaurosis is present." In cattle it is sometimes 

 caused by a deranged state of the brain from dis- 

 ease of the stomach, and is temporary in most 

 cases of milk fever. In this case when the animal 

 is cured it regains its sight. Amaurosis in most 

 cases is incurable. 



Punctures to the Eyeball. — This is an accident 

 which is likely to happen to any animal, caused by 

 it running its eye against something pointed, such 

 as a nail sticking out on some of the boards of the 

 manger, sharp ends of hay, straw or thorns. 



Symptoms: The eye is kept closed and there is 

 a copious flow of tears from it. On examination 

 the puncture will be easily seen. If it is only into 

 the cornea there will be an oozing of water, but if 

 it is deeper, the vitreous humor may be leaking; if 

 so, it resembles boiled starch with a purple tinge, 

 and if the opening is large it may all run out; if 

 it does so, there will be a shrinking of the eyeball, 



