do not grow ín the presence of air (anrerobic) but ihe germs 

 or spores are capable of living outside of the animal body for 

 a long time. 



Writers state that blackleg some times attacks other 



species of animáis, 

 than eattle, bnt \ve 

 have never observed 

 a case in other an- 

 imáis, either in Cuba 

 or the United States. 

 If it does occur in 

 other animáis it is so 

 rare that the losses 

 are insignificant. 



AGE. 



Blackleg usually 

 attacks calves bet- 

 ween twoand twenty 

 months of age, the 



Figure NÍ i , 



greatest losses oc- 



curring between the ages of six and eighteen months. After 



eattle are two years oíd they rarely contract blackleg. Some 



veterinary writers state that suckling calves do not contract 



blackleg, but we have observed this disease frequently in 



suckling calves both in the United States and Cuba, in fact 



it is quite common among suckling calves in Cuba. 



As a general rule calves that are fatand in good physical 



condition are more susceptible to blackleg than thin calves. 



It is well knpwn among cattlemen that blackleg usually 



attacks their best and fattest calves; although it inay attack 



calves in any condition offlesh. Sexorbreed, native or foreign 



does not seem to make any difference in their susceptibiüty 



to this disease. 



MODE OF INFECTION. 



Blackleg is generally considered by veterinary writers to 

 be a wound infection disease, but among a large number of 



