296 DISEASES OF ‘THE HORSE. 
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. When 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 may 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 eye have been incidentally alluded to under inflamma- 
tion of the lids. 
Filaria palpebralis 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- 
