STRANGLES— CORYZA CONTAGIOSA EQUORUM 359 



By direct contact with such an animal or one showing pro- 

 nounced symptoms of the disease susceptible horses are readily 

 infected. In a barn where strangles exists the air will be 

 more or less impregnated with globlets of discharge containing 

 streptococci, especially if the ventilation is bad. Mangers, 

 water buckets, troughs, stall partitions and floors contami- 

 nated with nasal or abscess discharge, may under favorable 

 conditions retain the infection for several months. There- 

 fore, horses placed in stables where the disease has existed or 

 if they are permitted to eat or drink out of infected buckets, 

 watering troughs, etc., may ingest the streptococci of the 

 disease. Livery and dealers' stables are thus more or less 

 permanent sources of infection, each year outbreaks occurring 

 in them. 



' Colts may infect their dams by nursing; stallions, mares 

 • during the act of coitus. Intra-uterine infection may also 

 occur. 



Some outbreaks which are not traceable to any recogniz- 

 able source may possibly be due to a saprophytic life which 

 the streptococcus is thought to assume. 



One attack of strangles usually affords life-long immunity. 

 There are, however, many exceptions, individual animals 

 suffering two or more attacks of the disease. 



Any factor (refrigeration, overwork, poor food and care, 

 etc.) which reduces the resistance of the horse predisposes it 

 to the disease. 



Necropsy. — The postmortem lesions are those of pyemia 

 with abscesses in lymph glands (mediastinal, bronchial, mes- 

 enteric) or in any of the parenchymatous organs. Broncho- 

 pneumonia or suppurative pneumonia with lung abscess alone 

 or combined with pleuritis and pericarditis is commonly 

 noted. In the abdominal cavity the mesenteric lymph glands 

 are found involved. In some instances a spontaneous rupture 

 of. the abscess has occurred leading to a diffuse purulent 

 peritonitis. In others a more chronic condition is noted 

 (adhesive peritonitis) with adherent loops of bowel. Where 

 there has been general metastasis, multiple abscesses may 

 form in any organ of the body (brain, muscle, thymus, 

 heart, etc.). 



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