338 Veterinary Medicine. 



ers and stable-men, but that it also has the source of vaccinated 

 persons in the families of those handling the horses. Whether it 

 was also often derived from the very prevalent small pox in past 

 times is doubtful, yet it appears to have been much more common 

 about the year 1800 than it is today. When once started in a 

 stable it passes readily from horse to horse, through the hands of 

 shoeing-smiths and grooms, including of course their aprons, 

 brushes, sponges and rubbers, and also through blankets, band- 

 ages, litter and other things on which the virus has been received. 

 The susceptibility of the skin in the hollow of the pastern depends 

 mainly on the frequency of chaps and abrasions, and to a certain 

 extent on contact with the road-mud infected by other passing 

 animals. At times the suffering animal licks the affected part, 

 and determines the eruption on the mouth, lips and nose (see con- 

 tagious pustular stomatitis). Megnin saw cases affecting the 

 external generative organs and transmitted between the sexes by 

 coition. (See vesicular eruption on the genitals). All such cases 

 should be identified by inoculation. 



Hertwig, as early as 1830 recorded the existence of horse-pox 

 in Berlin, where it has been seen frequently since, and noted its 

 transmission to man. Bouley gave evidence of its special preva- 

 lence at Paris, and of the production of typical vaccine vesicles 

 in man by its inoculation. More recently it has been frequently 

 observed and studied by inoculation and otherwise. 



Symptoms. These, whether seen in horse, cow or man, do not 

 differ from those of cow pox, with which it may be held to be 

 identical. The observations of Chauveau, Warlomont, and 

 Pfeiffer that experimental infection, intravenous, subcutaneous, in- 

 tratracheal (inhalation), or by feeding almost always failed to give 

 the general eruption which characterizes small pox and sheep pox. 

 It remains strictly local except when inoculated on other parts of 

 the skin or mucosa. It must be added, however, that small pox 

 or sheep pox, when inoculated successfully on the horse, as a 

 rule remains confined to the seat of inoculation. The constitu- 

 tion of the horse, like that of the cow, tends to resist its virulence. 



The affected horse may show preliminary febrile symptoms, 

 but these are usually too slight to be noticed. They are followed 

 by heat, tenderness and swelling of some part of the skin, usually 

 in the hollow of the pastern and perhaps the back part of the 



