4o8 Veie?'i7ia7y Medicine. 



The period of dentition and training is the most common 

 occasion for the attack, partly because this is the time when the 

 colt is taken from the pure air and exercise of the field, into the 

 hot, close, impure atmosphere of the stable, partly because he 

 is made to exchange the cooling succulent grass for the stimula- 

 ting ration of hay and grain, partly because he is subjected to 

 severe constraint and much excitement in the hands of the trainer, 

 and partly because of the irritation of the gums, the jaws and 

 the whole head in connection with the shedding and eruption of 

 the teeth. When injudicious bitting is resorted to, to give a 

 special curve to the neck, the consequent obstruction of the 

 jugulars and capillary congestion in the head is another potent 

 cause. Heavy draught and overdriving have a similar effect. 

 In 53 cases Schmidt found that 3 occurred under one year old, 

 5 in the 2d year, 10 in the 3d year, 16 in the 4tli, 15 in the 5th, 

 and 4 from the 5tli to the 9th years. 



Influence of Season. Mayer gives a statement of the per- 

 centages seen in the various months of the year as follows : 

 January 4.9%, February 4.7%, March 10.1%, April 15.1%, 

 May 13.4%, June 9.99^ , July 11.9%, August 6.4%, September 

 4.9%, October 6.2%, November 6.7%, December 5.2^/f, The 

 high rate in March, April and May may have a significance in con- 

 nection with the debility connected with shedding the coat, and 

 the resumption of more active work, when somewhat out of con- 

 dition, it must also be noted that this is in Germany the season 

 of the most active trade in horses and consequent change of 

 ownership, stabling, feeding, work and management. 



Heredity must be accepted as one of the most potent accessory 

 causes. The lymphatic constitution is of course transmitted and 

 with it the special su.sceptibility. This is notorious in the case 

 of both parents, and is of course more potent if both sire and 

 dam were predisposed, and have themselves suffered. In the 

 latter case. the heredity of t)ie lymphatic temperament, and of the 

 impaired organ of vision combine to render transmission more 

 certain. A mare may have born a number of .sound foals before 

 suffering from the malady and then have offspring that do contract 

 the disease. So with the stallion. Moller quotes the case of 

 the eastern horse Turk-Mayn-Atty which served for a length of 

 time in Prussian Studs and left a great stock of blind progen}^ 



