STRANGLES— CORYZA CONTAGIOSA EQUORUM 395 



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 globules of discharge 

 containing streptococci, especially if the ventilation is bad. 

 Mangers, water buckets, troughs, stall partitions and floors 

 contaminated with nasal or abscess discharge, may under 

 favorable conditions retain the infection for several months. 

 Therefore, horses placed in stables where the disease has 

 existed or if they are permitted to eat or drink out of infected 

 buckets, watermg 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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