296 DISEASES OF THE HOESE. 



the same in light and darkness. Ordinary eyes when brought to the 

 light have the pupils suddenly contract and then dilate and contract 

 alternately until they adapt themselves to the light. The horse does 

 not swerve when a feint to strike is made unless the hand causes a 

 current of air. The ears are held erect, turn quickly toward any 

 noise, and the horse steps high to avoid stumbling over objects which 

 it can not see. 



Treatment is only useful when the disease is symptomatic of some 

 removable cause, like congested brain, overloaded stomach, or gravid 

 womb. AVlien recovery does not follow the termination of these 

 conditions, apply a blister behind the ear and give one-half dram 

 doses of nux vomica daily. 



TUMORS OF THE EYEBALL. 



A variety of tumors attack the eyeball — dermoid, papillary, fatty, 

 cystic, and melanotic — but perhaps the most frequent in the horse is 

 encephaloid cancer. This may grow in or on the globe, the haw, the 

 eyelid, or the bones of the orbit, and can be remedied, if at all, only 

 by early and thorough excision. It may be distinguished from the 

 less dangerous tumors by its softness, friability, and great vascu- 

 larity, bleeding on the slightest touch, as well as by its anatomical 



structure. 



STAPHYLOMA. 



This consists in a bulging forward of the cornea at a given point 

 by the sacculate yielding and distention of its coats, and it may be 

 either transparent or opaque and vascular. In the last form the iris 

 has become adherent to the back of the cornea, and the whole struc- 

 ture is filled with blood vessels. In the first form the bulging cornea 

 is attenuated ; in the last it ma}^ be thickened. The best treatment is 

 by excision of a portion of the rise so as to relieve the intraocular 



pressure. 



PARASITES IN THE EYE. 



Acari in the qjq have been incidentally alluded to under inflamma- 

 tion of the lids. 



Filaria faJpeljralh is a white worm, one-half to 1 inch long, which 

 inhabits the lacrimal duct and the underside of the eyelids and haw 

 in the horse, producing a verminous conjunctivitis. The first step in 

 treatment in such cases is to remove the worm with forceps, then treat 

 as for external inflammation. 



Setaria equina is a delicate, white, silvery-looking worm, which I 

 have repeatedly found 2 inches in length (a length as great as 5 inches 

 has been reported) . It invades the aqueous humor, where its constant 

 active movements make it an object of great interest, and it is fre- 



