268 BUREAU OF ANIMAL INDUSTRY. 



patient sbould bo kept in semidtykiicss, or taken out only with a 

 dark sliade over the eye. For the same reason heav}- drafts and rapid 

 paces, which would cause congestion of the head, should be carefulh' 

 avoided. 



RECURRENT OPHTHALMIA (PERIODIC OPHTHALJNIIA, OR MOONBLIKD- 



NESS). 



This is an inflammatory affection of the interior of the eye, inti- 

 mately related to certain soils, climates, and systems, showing a strong 

 tendency to recur again and again, and usually ending in })lindness 

 from cataract or other serious injury. 



Causes. — Its causes may be fundamentally attributed to soil. On 

 damp clays and marshy grounds, on the frequently overflowed river 

 bottoms and deltas, on the coasts of seas and lakes alternately sub- 

 merged and exposed, this disease prevails extensively, and in many 

 instances in France (Reynal), Belgium, Alsace (Zundel, Miltenberger), 

 Germany, and England it has very largely decreased under land drain- 

 age and improved methods of culture. Other influences, more or less 

 associated with such soil, are potent causative factors. Thus damp 

 air and a cloudy, wet climate, so constantly associated with wet lands, 

 are universally charged with causing the disease. These act on the 

 animal body to produce a lymphatic constitution with an excess of 

 connective tissue, bones, and . muscles of coarse open texture, thick 

 skins and gummy legs covered with a profusion of long hair. Hence 

 the heavy horses of Belgium and southwestern France have suffered 

 severely from the aft'cction, while high drj* lands adjacent, like Cata- 

 lonia, in Spain, and Dauphin}-, Provence, and Languedoc, in France, 

 have in the main escaped. 



The rank aqueous fodders grown on such soils are other causes, but 

 these again are calculated to undermine the character of the nervous 

 and sanguineous temperament, and to superinduce the Ij^mphatic. 

 Other foods act by leading to constipation and other disorders of the 

 digestive organs, thus impairing the general health; hence in an}' ani- 

 mal predisposed to this disease, heating, starchy foods, such as maize, 

 wheat, and buckwheat, are to be carefully avoided. It has been widely 

 charged that beans, peas, vetches, and other Legumiriosie are dangerous, 

 but a fuller inquiiy contradicts this. If these are well grown they 

 invigorate and fortify the system, while, like any other fodder, if grown 

 rank, aqueous, and deiicient in assimilable principles, they tend to 

 lower the health and open the way for the disease. 



The period of dentition and training is a fertile exciting cause, for 

 though the malady may appear at any time from birth to old age, ^^et 

 the great majority of victims are from two to six years old, and if a 

 horse escapes the affection till after six there is a reasonable hope that 

 he will continue to rasist it. The irritation about the head during the 



