PREVENTIVE MEDICINE 283 



panied by abscess formation in the submaxillary lymphatic glands, 

 and at times in any other part of the body. It is considered by most 

 observers to be caused by the Streptococcus equi discovered in 1888 

 by Schiitz, though some have held that an ultravisible virus is the 

 real cause, the streptococcus being a secondary invader. Infection is 

 restricted to horses, asses and mules, though the last named animals 

 are more resistant. The other domesticated animals are not suscept- 

 ible. It is chiefly a disease of young horses but animals of any 

 age may be attacked. Seventy per cent, of cases occur in horses 

 under 5 years of age and only about 10 per cent, in horses over 

 15 years of age.* Healthy aged horses can resist large doses of 

 culture or abscess discharge. Todd failed to infect such horses 

 by smearing virulent material on the nostrils, by feeding with similar 

 material, and in one case by actually rubbing culture into the pre- 

 viously scarified mucous membrane of the nose. There is no special 

 seasonal incidence, though, according to Hutyra and Marek, out- 

 breaks are more commonly seen in the spring. Predisposing causes 

 are any conditions which tend to lower the vitality, e.g., bad 

 weather, long train journeys, long voyages, fatigue, recent illness, 

 and, especially in young horses, any sudden change, e.g., of food, 

 environment, &c. 



The disease has been known since early times and is more or 

 less universally distributed throughout the United Kingdom. It 

 is usually supposed to be contracted by ingestion of food or water 

 contaminated with nasal or other discharge from a pre-existing 

 or accompanying case, but the spread is also facilitated at times 

 by attendants' clothes and hands, harness, bedding, &c. Want of 

 surgical cleanliness such as the careless use of a scalpel after opening 

 an abscess has been known to spread the disease, and notably so at 

 castration. Infection has been known to pass from dam to foetus, f 

 from stallion to mare during coitus, and also from foal to mare 

 during sucking. It is improbable that the streptococcus multiplies 

 to any great extent in nature (as Schiitz believed) and the organism 

 is generally regarded as being obligatory. Outbreaks are thus 

 never sporadic, the disease being introduced into a stud in the first 

 place by an infected or may be convalescent animal. There is 

 evidence that the streptococcus may be present for long periods 

 in the nasal cavities of horses which have recovered from an attack, 

 and such animals may act as " carriers." In this connection it 

 is important to note that it has been proved by clinical evidence that 

 cases of simple catarrh or so-called " catarrhal fever " are in reality 



* Todd, Journ. Comp. Path., 1910, Vol. XXIII. 

 t Choisy and Nocard, Journ. Comp. Path., 1888, Trans., Vol. I. 



