344 DISEASES OF CATTLE. 



Causes. — It may arise spontaneously or follow a scar after an 

 injury. 



Symptoms. — Kelis generally appeai-s below the knee or hock. It 

 may occur singly or in numbei-s. There are no constitutional symp- 

 toms. Its growth is very slow and seldom causes any inconvenience. 

 It appears as a flattened, irregular, or spreading growth within the 

 substance of the skin, is hard to the touch, and is especially charac- 

 terized by divergent branches oi* roots, resembling the claws of a crab, 

 and hence the name. Occasionally some part of it may soften and 

 result in an abscess. It may grow" several inches in length and 

 encircle the whole limb. 



Treatment. — So long as it causes the animal no inconvenience it is 

 best not to meddle wdth it; when it does, the animal ought to be 

 fattened for beef, the meat being perfectly harmless to the consumer. 



PARASITIC DISEASES OF THE SKIN. 



MANGE, ITCH, SCAB. 



[See discussion in chapter on " Tlie animal parasites of cattle."] 



LOUSINESS. 



[See discussion of lice in chapter on " The animal parasites of cattle."] 



WABBLES, OB GBUB IN THE SKIN. 



[See dlscHSsioni'in chapter on " The animal parasites of cattle.''] 



BUFFALO GNATS. 

 [See discussion of these parasites in chapter on " The animal parasites of cattle."] 



HOBN FLY (H.EMATOBIA SERRATA). 

 [See discussion of this parasite in chapter on " The animal parasites of cattle."] 



TICKS. 

 [See discussion of these parasites in chapter on " The animal parasites of cattle."] 



FLIES. 

 [See discussion of these parasites in chapter on "The animal parasites of cattle."] 



RINGWORM (tinea TONSURANS AND TINEA FAVOSA). 



RingTf\'orm is an a flection of the skin, due to a vegetable parasite. 

 Tinea tonsurans is due to the presence of a minute or microscopic fun- 

 gus — the Trichophyton tonsurans. It affects the hair and the epi- 

 dermic layer of the skin, and is highly contagious, being readily 

 transmitted from one animal to another. This fungus consists of 

 spores and filaments. The spores, being the most numerous, are 



