DISEASES OF THE OX AND SHEEP. 255 



The malady generally attacks calves which are from three to 

 six months old, and although the disease may occur in oxen of 

 any age, it is very seldom met with in cattle which are more 

 than two years old. Moreover, it is generally one-year-old 

 sheep that are liable to be afflicted, and it is very rare that 

 animals above two or three years old go down with the disease. 

 It is, however, believed that this apparent immunity of older 

 animals is due to the fact of their being located in one district, 

 and seldom or never being moved ; for in Algeria, where the 

 animals are moved from place to place, this immunity does not 

 exist. It is important that stringent preventive and remedial 

 measures should be taken, for otherwise the disease may spread 

 and pursue its rapid and fatal course. 



It is contended by some that black-leg is a disease caused by 

 plethora, that is to say, nutrition beyond the limits of health ; 

 and that the best and iattest animals are those most subject to 

 attack. Now, although the disease not uncommonly does 

 manifest itself in the best-nourished animals, it must be pointed 

 out that the high condition of the animal is not be regarded by 

 any means as the primary factor in the causation of the disease. 

 It often happens that scarlet fever and measles and other fevers 

 of mankind invade the more healthy members of a family, while 

 the others perhaps escape altogether, yet who would say for a 

 moment that a healthy condition of the body was a cause of 

 scarlet- fever or other fevers ? 



It is said that black-leg is especially liable to affect young 

 cattle, taken from a poor to a rich pasture, and especially to 

 low-lying pastures ; but we think it is the change from a non- 

 contaminated to a contaminated locality which is the real cause 

 of outbreaks of both black-leg and anthrax. 



Black-leg in most instances attacks animals out at grass, but 

 those in the yard do not by any means always escape. It is 

 hardly necessary to speak at great length of the symptoms of 

 this disease, many of our readers unfortunately being already 

 too well acquainted with them. The symptoms are somewhat 

 as follows : — Certain of the best animals of a herd or flock, or of 

 the oxen in the stalls, may perhaps be observed to look dull 

 and listless, and to move with difficulty, and, in fact, to be lame 

 on one or two of the limbs, either hind or fore. The poor 

 creatures rarely move, their limbs are stiff and rigid, and if the 



