HORSE— CARE AND MANAGEMENT. 



73 



of incubation, during which the poison 

 germs are in the body of the animal, and 

 propagating themselves there, but have 

 not yet affected the constitution so as to 

 impair the functions, or give rise to the 

 more manifest symptoms of illness. To- 

 ward the end of this period, however, the 

 thermometer shows an increase of tem- 

 perature, in the interior of the body, of 

 about two degrees beyond the natural 

 standard. This period lasts twenty-four 

 to forty-eight hours, though in rare cases 

 it may apparently extend to a week. 



It is followed by the period of eruption, 

 which is first manifested by the redness, 

 heat, and tenderness of the udder and 

 teats, of the space between the hoofs, and 

 -of the membrane of the mouth. In the 

 course of one day more, these parts are 

 found to be the seat of numerous hemis- 

 pherical elevations or blisters, caused by 

 the effusion of a clear, yellowish fluid 

 from the blood-vessels beneath the cuticle 

 •or scarfskin. These increase in size for 

 the next two or three days, burst, and dry 



The period of decline is marked by the 

 •drying and scabbing over of the sores 

 caused by the rupture of the blisters, and 

 by the reproduction of the lost cuticular 

 covering or scarfskin. The elevated tem- 

 perature, which had declined somewhat 

 on the appearance of the blisters, now en- 

 tirely subsides, unless maintained by ex- 

 posure, or the irritation of the sores by 

 dirt or other bodies. This period has 

 passed and the disease is at an end by the 

 fifteenth day, in favorable cases. 



Causes. — The only known cause of 

 Itself capable of inducing the disease is 

 contagion, or contact of a sound animal 

 with the virus discharged trom the sores 

 of an aphthous patient. Many accessory 

 causes may be named, such as a wet, 

 muddy season, which insures the contact 

 of the virus deposited on the soil with the 

 skin about the top of the hoofs ; the ac- 

 cumulation of cattle in large fairs or mar- 

 kets; the aggregation of large numbers 

 •of live stock for the supply of armies in 

 the field; travel of stock by rail or road, 

 and the like. Yet these are but means of 

 the diffusion of poison, while no one of 

 them, nor all taken together, can call the 

 •disease into existence where the poison is 

 not already present. Though prevalent 

 extensively in Europe during or after 



almost every great war since 1695, it did 

 not reach Great Britain till 1839, when it 

 was brought by some Dutch cattle im- 

 ported into London. In the same year 

 it was brought by Dutch cattle to Cork, 

 Ireland ; and, as free trade in continental 

 cattle was established four years after, it 

 has been since steadily maintained by the 

 constant importations. In 1 84 1 it Avas first 

 reported in Denmark, a country which 

 breeds its own stock, and rarely imports 

 any. In the year 1872 was the first 

 time it appeared on American soil, and it 

 has not yet reached the great stock ranges 

 of Australia. In Great Britain it spreads 

 widely every year, after the great autumn 

 markets, in which home and foreign store 

 cattle mix freely; and yet there are in 

 that country many breeding districts into 

 which strange stock are never taken, and 

 where the disease has not yet penetrated. 

 It prevails very frequently on cattle deal- 

 ers' farms in the same country. 



Such comprehensive facts as these nar- 

 row the list of real causes down to the 

 simple contact of the virus with a healthy 

 animal. This virus, however, is perhaps 

 the most contagious known. It is often 

 carried on the clothes, boots, and hands 

 of men; on the fibres of hay or straw; 

 preserved on the walls, floors, mangers, 

 and other fittings of buildings ; on stable 

 utensils ; in yards, parks, roads, and rail- 

 road cars; on drinking troughs; or it 

 may be carried on the legs or bodies of 

 dogs, chickens, rats, and other animals 

 which themselves escape the infliction. 

 In short, any solid body may retain and 

 be a bearer of this contagion. Fortu- 

 nately, it does not spread to any extent 

 in the atmosphere. Nothing is more com- 

 mon than to find a herd on one side of a 

 road struck down by the disease, while 

 another in a field on the opposite side of 

 the road remains perfectly healthy. It 

 may be carried by a strong wind in the 

 form of the virulent saliva, or the virus 

 may dry up on light bodies, such as paper, 

 hay, etc., which are afterward borne off 

 by the wind. It may be carried by men 

 or animals, or by water running from the 

 diseased to the healthy lot ; but, in the ab- 

 sence of such agencies, the breadth of a 

 common road is amply sufficient to cir- 

 cumscribe the disease. 



Susceptibility of Different Ani- 

 mals. — Cloven-footed animals appear to 



