VETEEINARY DEPARTMENT. 155 



mals in a certain locality, or it may be confined to a single farm, while the 

 term opthalmia, is now universally applied to certain diseases of the eye, 

 both in human and veterinary medicine. 



THE CAUSE OF THIS DISEASE, 



like the cause of many similar enzootics, is still wrapped in deep obscurity. 

 I need hardly say that I do not believe in the lark-spur theory. Then there 

 are those who say it is the result of fatigue, from over-driving upon dusty 

 roads for instance, or exposure to cold, after shearing, or, indeed, at anytime, 

 and that sudden changes of the weather are liable to bring on an attack. 

 Although it may be true that any debilitating influence, such as exposure, etc., 

 is liable to render an individual more susceptible to the complaint, yet I can- 

 not think that that alone will produce it. Indeed, it seems to have no 

 respect for the condition of the animal, breed, or sex, age or size, or other 

 circumstance that I can suggest, unless I take advantage of that now fash- 

 ionable way of accounting for the existence of certain maladies, and con- 

 demn it as a "malarial trouble;" for it is not at all improbable that a spe- 

 cific virus floating in the air, and finding a suitable habitat in some sheep, 

 will perform its various eccentricities. 



SYMPTOMS. 



The complaint is easily recognized, as several animals in a flock will 

 become suddenly blind, without any apparent cause. Taking a casual look 

 at the malady, one cannot help being impressed with the similarity between 

 this disease and Pinkeye in horses; but closer observation will show with 

 tolerable certainty that they are two distinct disorders. 



On watching the course of enzootic opthalmia in sheep, from day to day, 

 we will find, first of all, that the ball of the eye, instead of presenting that 

 bright, glistening appearance, characteristic of it, will be dull or opaque 

 looking, the eyelids will be inflamed, and the animal will not be able to tol- 

 erate light, but be constantly blinking; tears will flow profusely over the 

 cheek, and there will be more or less discharge (of tears) from the nose. In 

 the course of a day or two, the eyes will appear redder and larger, which con- 

 dition will often be accompanied with, or followed by angry looking sores. 

 These are seen, sometimes, to eat their way through the eye-ball, and 

 allow the internal structure of the eye to escape : that is, the fluid portion ; 

 when the internal structures become involved, a cataract and permanent 

 blindness is liable to be the result. 



This ulceration never occurs in Pinkeye in horses, that I am aware of, nor 

 does it in mild cases in the sheep. 



The constitutional symptoms, like the local, vary considerably with the 

 individual. In some I have found but slight fever, while the clinical ther- 

 mometer would indicate considerable elevation of temperature in the next 

 one examined — ranging from 102° to IDS'' Fahr. Some animals lose their 

 appetite while others eat tolerably well, the bowels become more or less con- 

 stipated, unlike pinkeye, is there that disturbed condition of the alimentary 

 canal so often noticed in the horse. Nor does there appear to be the same 

 tendency for sheep to abort, as there invariably is with the mare in the latter 

 half of pregnancy. 



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