Chronic Keratitis. 385 



This is especially common in dogs in warm latitudes. Trichiasis 

 and entropion are perhaps the most common of the direct causes. 

 Eczema and other skin eruptions affecting the lids are additional 

 causes, while old and debilitated dogs are especially subject to the 

 affection. It is less frequent in horses. 



The symptoms are much less severe than in the acute form. 

 The lids are usually partially but rarely completely closed, 

 lachrymation may be absent and is never excessive, the secre- 

 tion usually sticks together the cilia and lids, and always forms 

 crusts on them, the palpebrse are less sensitive than in acute 

 keratitis, the cornea is habitually clouded of a bluish- white color, 

 yet in the main partially transparent and without the disc 

 opacities of the acute tj^e of disease, and the pupil, which is 

 usually visible in a good light or under oblique illumination, may 

 be slightly but is not excessively contracted. The surface of the 

 cornea seems to have lost some of its polish, and in its sub- 

 stance blood vessels can usually be made out. 



Under favorable conditions these cases may end in resolution 

 and especially under a change of food and environment. In 

 less fortunate cases they result in a fibroid degeneration of the 

 cornea and deep permanent opacity. 



Treatment. It is usually desirable to change the regimen so 

 as to improve the general health, and to allow a fair amount 

 of out-door exercise. In the very old and debilitated the case 

 is rather hopeless. A course of iron or bitters will sometimes 

 have a good effect. In other cases sulphide of calcium ^V grain 

 thrice a day will prove useful. Eczema must be treated se- 

 cundum artem. 



Ivocally astringent and antiseptic collyria may be used as in 

 the acute form. Atropia, 5 grs. to the oz., is a valuable ad- 

 juvant, to be instilled in drops. Ointment of yellow oxide of 

 mercury, a piece like a pin head rubbed inside the lids once 

 or twice a day often acts well. Finally Trasbot strongly com- 

 mends liquor of Van Swieten. 



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