182 THE MODERN HORSE DOCTOR 



subsided ; but a relapse manifesting itself in one or both eyes, 

 soon undeceives us. 



Causes of Periodic Ophthalmia. — The disease may be in- 

 duced by a variety of exciting causes; hereditary influence is 

 supposed to be one among the many causes prolific of the malady ; 

 yet veterinarians are undecided in their opinions as to whether 

 the disease itself, or only the predisposition, is transmitted. Mr. 

 Percivall considers hereditary influence as "predisposent only — 

 not excitant; nor sufficient of itself to produce ophthalmia." 

 Professor Coleman teaches, in his Lectures, that " the disease is 

 never seen prior to the domestication of the animal ; never occurs 

 on a common or in the open air, but is the product of the poison 

 generated from the effluvia of the breath, dung, and urine of 

 horses standing together ; in proof of which the disease is found 

 to be more or less prevalent, according as the stables in which 

 horses stand are ventilated. In stables that have the most cases 

 of inflamed lungs, grease, and glanders, there we find the most 

 blindness ; and where these diseases are rarest, ophthalmia is 

 least known. Coincident with the opinion of Coleman, and we 

 may add Percivall and many other writers, is the experience of 

 the author, and many intelligent horse dealers of the United 

 States also ; for the disease, in the first place, is not so prevalent 

 here as in the crowded cities and barrack stables of the old 

 world ; and, secondly, we do not find so many blind horses here. 

 Whenever a case of simple or specific ophthalmia occurs, we 

 generally find the subject located in a filthy stable, or on low, 

 marshy ground, or else he has been shut up for many hours in a 

 railroad car, there respiring over and over again the foul products 

 of combustion and excretion. The disease, as a matter of course, 

 maybe induced by mechanical means, — through injuries sus- 

 tained, — or by violating, in the stable management of the animal, 

 some physiological law. The disease induced in this way may 

 at times, assume in its primary stage, the form of simple ophthal- 

 mia, and afterwards degenerate into the disease now under con- 

 sideration. 



The use of blinders, which are now fast going out of fashion, 

 must tend to irritate the eyes of horses ; and the sooner they are 

 entirely dispensed with, the better will it be for both horse and 

 owner. 



