Natural Infection. 369 



there is a desquamation of epithelium, or by deep penetrating 

 injuries. 



The disease occurs usually when affected or not entirely 

 recovered animals are introduced into the stable. The outbreak 

 of the disease in the studs of Mezohegyes is usually associated 

 with the introduction of colts purchased from different parts, 

 and from similar causes the disease frequently develops in colts 

 at remount depots. According to the investigations of Jolly & 

 Leclainche scabs from an exanthema of the skin of colts affected 

 with strangles may also disseminate the infection. 



The air evidently plays an important part in the transmis- 

 sion of the infection, inasmuch as in the warm and moist stable 

 air the virus expelled during coughing and blowing may float 

 for a considerable time attached to the droplets, and later enter 

 the upper air passages of healthy animals. This form of trans- 

 mission through the air is less dominant out of doors, first 

 on account of the smaller quantity of moisture, and second on 

 account of its more rapid movement, which results in the rapid 

 dilution of the expelled virus. 



Through contamination with nasal discharge and pus from 

 the glands the most varied objects may become carriers of the 

 infection, such as cribs, drinking utensils, the food, the drinking 

 water, straw, walls, floor of the stables, the grass in the pasture, 

 further the hands and clothes of the attendants. The fresher the 

 secretion the greater its virulence; drying hoAvever does not 

 wholly destroy its infectiousness. The disease usually occurs 

 annually almost at the same time of the year in stables of colts, 

 if they have not in the meantime been cleaned and disinfected. 

 It usually appears in the spring, and it is not possible in all 

 instances to prove a fresh introduction from the outside. In 

 such cases it must be assumed that the virus remained in the 

 stable after the disappearance of the disease, and was there 

 dormant for months until it again attacked the susceptible indi- 

 viduals of the new generation of colts, and thereby caused a new 

 outbreak of the disease. 



The infection probably enters from the digestive tract, 

 and especially through the intestinal mucous membranes in 

 those cases in which it affects primarily or exclusively, the 

 Ijaiiph glands of the mesentery. However up to the present 

 time it has not been possible to produce this form of the disease 

 by feeding infected food. 



In copulation an infected stallion may transmit the disease 

 to mares, and in such cases there appear symptoms of a vaginal 

 catarrh, while the Ijanpli glands in the vicinity of the external 

 genital organs and of the rectum, as well as in exceptional 

 cases also the udder, become affected (van Leeuwen, Preuss. 

 V.-B., Bierstedt). Affected colts may infect their mothers dur- 

 ing sucking and cause an inflammation of the udder and the 

 neighboring haiiph vessels (Bermbach; in one case necrosis of 

 one half of the udder and later a fatal septicemia resulted). 



