64 



A rheumatic condition of the system is said to play an 

 important part among the long list of causes of moon- 

 blindness. It, however, like many other depressing diseases 

 and influences, is only a preparing or predisposing cause 

 or condition which can not originate the disease but may 

 excite frequent attacks and increase its severity. , Smoke? 

 pungent vapors, hayseeds, dust or any local irritants or 

 injuries may awake the latent tendency or augment the 

 intensity of an attack. In short, whatever depresses the 

 vigor or debilitates the system will aid in originating the 

 disease and will also increase the intensity and frequency of 

 the attscks; anything that strengthens the constitution or 

 improves the animal vigor will be a protective or assist in 

 preventing periodic opthalmia. 



The essential and originating cause is very probably a 

 microbe, a miasmatic germ, an animal, worm-like parasite or 

 the poisonous product of a germ. The natural habitat or its 

 native place of propagation and development seems to be on 

 moist lands that are, during one season, extremely wet and 

 at other times dry enough to bring forth crops. The surface 

 water of such districts, and the fodders, grasses and hays 

 grown on such lands, transmit or carry the germs into the 

 system of the animal. 



During January, 1893, the veterinary department issued 

 about two hundred circular letters containing questions rela- 

 tive to eye diseases among domestic animals; these were 

 mailed to farmers and stockmen in all the counties of Ala- 

 bama, and they were also published in many of the daily 

 and weekly papers of the State. The principal question in 

 the circular letter read as follows : 



"Are horses and mules in your beat or county affected 

 with what is commonly called moonblindness? If you 

 have such an eye disease please state how frequently it oc- 

 curs, and what is your view of the cause of it." 



I received in all nearly 125 replies. From these replies 

 I have obtained the following records on periodic opthalmia 

 or moonblindness : 



