5S0 TIIH DISEASES OF THE HORSE 



bands of lympli wh'uh curtail its movements, and after repeated attacks 

 the Inimours become opaque and tlie lens is also involved. 



S}/mj)toms. — These are very much like those of simple ophthalmia or con- 

 junctivitis but not perhaps so acute, more gradual in their manifestation 

 and more lasting. " Ten days in coming and ten days in going " is a 

 connnon estimate of its duration. 



Treatment. — An aloetic ball, followed by small does of iodide of potas- 

 sium and the local treatment recommended for ordinary iiiilammation. 

 With a view to keeping the iris moving alternate doses of belladonna and 

 opium have been recommended. 



CATARACT 



C.VTARACT, or opacity of the lens, is very commonly the result of iritis, 

 its capsule having been coated with a layer of white lymph, deposited by 

 the inflamed vessels ; but it also sometimes makes its appearance without 

 being preceded by any of the signs of inllannnation. In the former case, 

 the early .symptoms are those of iritis ; but in the latter, the opacity often 

 goes on increasing, without the owner of the horse, or his groom, having his 

 attention drawn to the eyes, until he finds that he is nearly blind. This 

 progress is generally marked by the development of an unusual timidity ; 

 the previously bold animal is alarmed at objects advancing on the road, and 

 covered carts and Avaggons, of which he formerly took no notice, occasion him 

 to shy in the most timid manner. On examining his eyes carefull}', instead 

 of the beautifully clear pupil, with the reflection of tapetum hicidum shining 

 through it, there is seen either a mass of dull white, generally more opaque 

 in the centre, or an appearance of mottled, semi-transparent soap, or, lastly, 

 one or two distinct white spots, not quite circular, but with irregular edges. 

 In confirmed cataract, the white pupil can be seen at any distance ; but in 

 the very early stage, only a practised eye can detect the opacity, which, 

 however, is so manifest to him, that he wonders it is not visible to every 

 one else. The reason of this difficulty of detecting the alteration of structure 

 seems to be, that inexperienced examiners look at the eye in such a manner 

 that they are confused by the reflection on it of their own faces, hiding all 

 beneath. If, however, they will turn their heads a little more on one side, 

 this will disappear, and they cannot fail to perceive the disease. "When 

 cataract is clearly proved to exist, all idea of treatment may be abandoned, 

 as nothing but an operation can procure a removal of the opacity ; and that 

 would leave the horse in a more useless condition than before, since he 

 could see nothing clearly, and would only be subject to continual alarms. 

 In the human being, the operation is performed with great success, because 

 the lens which is sacrificed can be replaced externally by means of convex 

 glasses ; but in the horse, nothing of the kind can be done. Hence, it is 

 useless to dream of efiecting any improvement in this disease ; and if both 

 eyes are the subject of cataract, the horse is incurably blind. But supposing 

 there is a cataract in one eye only, is the other sure to go blind, or may a 

 reasonable hope be entertained of its remaining sound ] Here the history 

 of the disease must be examined before any opinion can be formed. If the 

 opacity followed an accident, there is no reason for concluding that the 



