AGRICULTURAL COLLEGE BULLETINS, 



No. 22.— VETERINARY DEPARTMENT. 



OBSERVATIONS ON A DISEASE AFFECTING THE EYES OF SHEEP. 



During the summer and autumn of last year, my attention was called to a 

 disorder among sheep, which aSects their eyes in such a manner, that it will 

 sometimes leave them blind in one or both organs; fortunately, though, the 

 disease yields to treatment in the majority of instances, not, however, before 

 going through a stage of very acute inflammation, causing much inconven- 

 ience, and suffering to the afflicted animal. 



THE DISEASE, 



as I have had occasion to observe it, breaks out in a flock, attacking one ani- 

 mal after another, in such a manner, as would naturally give one the impres- 

 sion, that it is of a contagious nature. At the same time, a very large propor- 

 tion which are exposed, seem to be armed with that peculiar weapon, "im- 

 munity," which renders them proof against an invasion. 



In comparing my observations of the complaint, with descriptions of the 

 diseases of sheep, by various authors, I was struck with one account, by a 

 well known writer upon veterinary topics (Youatt), who, writing in the early 

 part of the present century, and quoting, in substance, an old shepherd says: 

 " That sheep, when wandering over the moors, will sometimes accidentally 

 tread upon a lark's nest; that the old bird, becoming alarmed as to the 

 safety of her offspring, will rise up, like a game chicken, and spur the 

 intruder in the eyes, and it (the sheep) is then said to be 'lark-spurred.' " 



From the above it can be imagined how popular the term, "lark-spur" 

 would become among attendants upon sheep; besides, it was an easy way of 

 accounting for the appearance of the malady. Under the circumstances, 

 the disease was frequently left to run its course, and, as a result, cataract, 

 with total blindness, was a common termination. So common has the term 

 "lark-spur" become in some countries, that it is applied to nearly all dis- 

 eases affecting the eyes of sheep, by certain people. 



IN NAMING THE DISEASE, 



I think the most appropriate term which can be applied to it, is " Enzootic 

 Opthalmia;" for, like other enzootic diseases, it attacks a number of ani- 



