Natural Infection, Pathogenesis. 37;[ 



a high elevation to cold winds, and being further provided v^ith cold water to drink. 

 According to Cagny the disease occurs in certain localities of France less fre- 

 quently and runs a milder course since the colts are driven home from the pas- 

 tures in the month of September. 



Pathogenesis. The streptococci wliicli reach the surface of 

 the nasal mucous membrane, colonize in the numerous side 

 cavities of the upper air passages, and after multiplying there 

 they penetrate the mucous glands, from which they pass into 

 the Ijanph spaces of the tissue of the mucous membranes, along 

 which they gain entrance to the submaxillary lymph glands. In 

 case of an infection from the mucous membrane of the pharynx, 

 intestines, or vagina, they are held up in the neighboring hnmph 

 glands. 



Under the local influence of the penetrating bacteria 

 hyperemia and serous infiltration of the tissues develop, also 

 in some places necrosis of the superficial epithelial layer of 

 the mucous membrane. Serous fluid oozes from the surface, 

 and at the same time the secretion of the mucous glands is 

 increased. In the Ijanph glands a migration of the leucocj^tes 

 commences under the positive chemotactic action of the strep- 

 tococci or their toxins, and probably also because of an increase 

 of lymphocytes. The glandular tissue proper however becomes 

 partly dissolved, probably under the influence of a peptonizing 

 ferment. In this manner large suppurative areas develop in 

 the Ijanph glands, the tissues surrounding them showing usually 

 a marked swelling, due to inflammatory edema. 



Superficial abscesses usually open through the outer skin, 

 in which case the body rids itself of the infective substance. 

 From the first affected lymph glands, however, the bacteria 

 may pass along the lymph vessels to the neighboring, as well 

 as distant lymph glands in the body, in which they cause similar 

 inflammatory processes. Besides this the streptococci may 

 enter the blood stream by their power to penetrate the walls 

 of the vessels, and may thus be carried to all parts of the body, 

 producing metastatic abscesses in various organs aside from 

 the IjTnph glands, or they may cause a general septicemia. 



The acute inflammatory character of the local disease process, and 

 the associating febrile manifestations indicate that the streptococci 

 exert their pathogenic action through toxins. As a matter of fact the 

 experiments conducted with Rosenhach's streptococcus gave positive 

 results (Marmorek, Baginsky & Sommerfeld, Marmier and others), and 

 the pathogenic action of the toxin of this streptococcus manifested itself 

 in local acute inflammation, fever, and diarrhea. In less severe intoxi- 

 cations, emaciation and sometimes paralysis resulted. Some strains 

 produce toxins which possess hemolytic properties (Besredka, Neisser 

 & Wechsberg and others). 



In exceptional cases foals may be born with the affection 

 (Nocard, Choisy). The ability of the streptococci to penetrate 

 the walls of the vessels explains the occurrence of intrauterine 

 infection. In such cases pharyngitis and suppuration of the 



