THE SKIN 153 



Necrobacillosis, Actinomycosis 



Necrobacillosis is a very common cutaneous disease 

 in swine. Cutaneous actinomycosis and tuberculosis 

 occur less frequently. These conditions of the skin will 

 receive consideration under the special topics of necro- 

 bacillosis, actinomycosis, and tuberculosis, in Section 

 VIII. 



Tumors 



Pigmented moles are of frequent occurrence in the 

 skin of swine. These moles are sometimes pigmented 

 with melanin, and when interfered with develop into 

 malignant melanosarcomas. Many pigmented papil- 

 lomas and papillo-fibromas are also encountered in the 

 skin of swine, w^hile multiple fibromas have been observed, 

 they are not at all common. More rarely have primary 

 or even secondary carcinomas and epitheliomas been 

 recorded as cutaneous tumors in swine. 



Parasites 



Swine harbor many cutaneous parasites, some of 

 which are exceedingly detrimental to the health of the 

 animals. 



Of the dipterous group one only, the Campsomyia 

 macellaria (screw- worm), requires special mention. In 

 some sections these parasites cause considerable damage 

 and some fatalities. The larvae only are parasitic, the 

 adult female depositing the ova in wounds or damaged 

 tissue. The ova hatch in from one to ten hours and 

 immediately begin to burrow into the surrounding 

 tissues. The fully developed larvae are about one- 

 half of an inch long and about one-third the diameter 

 of a lead pencil. The damage consists not " only of 

 mechanically lacerating the tissues but also of carrying 

 infection into the surrounding tissues. The larvae 

 remain in the tissue from four to six days, then drop to 

 the ground, where they undergo the pupal metamor- 

 phosis. 



The time-honored treatment consists of curetting the 

 wound, thus removing all the larvae possible. It may be 



