288 WESTERN GRAZING GROUNDS AND FOREST RANGES 



fully for animals with small swellings on the jaw or 

 side of the face, and reject them on suspicion. At the 

 market animals with the disease are thrown out by the, 

 government inspectors and given a careful examination, 

 with the result that a large number of them are allowed 

 to go to slaughter as fit for human consumption. 



Blackleg. This is a disease of the blood. It is 

 infectious but not contagious, and confined almost wholly 

 to animals between the ages of eight months and two 

 years. Probably 80 per cent of all the deaths from 

 blackleg are confined to animals between ten and four- 

 teen months old. Cases where cattle over two years old 

 have died from it are extremely rare and the number 

 dying under eight months is not large. 



The disease has certain well-defined peculiarities. 

 There are seldom any outbreaks of blackleg during 

 a wet season, hence a certain area will be free from the 

 trouble for several years. During a dry year when the 

 dust about watering-places and salt-grounds is deep 

 and blown about by the wind, stockmen prepare for a 

 loss by blackleg. As a general thing, the fall is the 

 favorite time for the appearance of blackleg, although 

 a dry spring will develop it under certain conditions. 

 These conditions depend upon the physical condition 

 of the animals. As a rule, the disease attacks the flower 

 of the herd. The fatter and better bred the animal, the 

 more likely it is to have blackleg. Seldom does the 

 disease attack a poor animal, and as most range cattle 

 are far from fat in the spring, it doubtless is due to 

 this fact that the losses are more common in the fall. 

 After the summer season everything is fat and in excel- 

 lent condition to contract the trouble. 



Another thing that seems fairly well established 



