SPECIFIC INFECTIVE DISEASES 163 



organisms circulate in the blood and various other 

 tissues of the body, but in the horse the principal lesions 

 are found in the spleen (melt), and in the lungs. A horse 

 having this disease gradually becomes emaciated, until 

 it is either destroyed or else succumbs. The symptoms 

 are usually obscure. Sometimes excessive urination 

 accompanies this trouble ; at other times it does not. 

 Tuberculin is the only reliable method of testing for the 

 existence of this disease. 



Actinomycosis 



This disease is due to the ray fungus, or actinomyces 

 and it sometimes attacks the tongue of the horse an 

 foal, whilst there is a corresponding disease not uncom- 

 monly affecting the spermatic cord, following castration. 

 The disease first named is fairly common in cattle, 

 being known as woody tongue. Sometimes it affects the 

 skin and the udder of the mare, but it is by no means a 

 common disease in the horse, apart from the exception 

 referred to. (See also Castration.) 



