CONJUNCTIVAL OPHTHALMIA. 73 



under eyelids, as well as the covering of the fore part of the 

 membrana nictitans. From a common resemblance in structure 

 and economy, from the same kind of exposure, and from suscepti- 

 bility to the operation of similar causes, the conjunctiva, often 

 simultaneously with the membrane of the nose, takes on inflamma- 

 tion. When a horse has a catarrhal affection, what is more common 

 than to perceive at the same time that his eyes are weak, and are 

 pouring forth mucous or even purulent matter from their inner 

 canthi, and, perhaps, over the borders of the lower eyelids as well ] 

 The animal has evidently got " a cold in his eyes," as well as one 

 in his nose and throat : in proof whereof, inversion of the lids will 

 show the conjunctive membrane reddened, more or less tumid, and 

 injected. Indeed, in most inflammatory affections of the air- 

 passages and lungs, in encephalic inflammations, and in dental 

 irritations, we shall find the conjunctiva more or less participating 

 in the increased action ; and so much attention did former practi- 

 tioners of horse medicine pay to the state of this membrane, and 

 such importance attach to it, that it constituted, in constitutional 

 diseases, their guide — their sole guide very often — in respect to 

 the expediency of blood-letting, and the quantity of blood they 

 ought to take away : nor is the indication totally disregarded by 

 many very good practitioners among veterinary surgeons. Such 

 conjunctival inflammation, however, can be regarded but as sym- 

 pathetic in its origin and nature, increasing and subsiding with the 

 main disease present in the system : to the latter, consequently, we 

 devote our undivided attention, heeding the former but in the light 

 of a thermometer, or guide to a certain extent in our therapeutic 

 proceedings. 



I have, however, met with idiopathic conjunctival inflammation. 

 I have known horses turned into straw-yards at certain seasons of 

 the year, during the prevalence of cold drying winds, exhibit most 

 unequivocal symptoms of this disease, unaccompanied even with 

 any catarrhal disorder. I acknowledge, however, that such cases 

 are rare; and that the ordinary cause of this inflammation is 

 injury of some sort. It is far from being an easy matter to answer 

 the question, why horses' eyes should not be subject to the various 

 conjunctival diseases which affect our own : certainly, the conjunc- 



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