156 SWINE DISEASES 



pairs of legs, but they have 110 sexual organs. In two or 

 three days the nymphse moult and the sexually matured 

 males and females come forth. The sexually matured 

 parasites mate, and in about three to five days the 

 ovigerous female is found in the gallery in the skin, 

 ovulating. Thus the entire life cycle does not exceed- 

 twenty-five days, and under the most favorable condi- 

 tions may be accomplished in fifteen days. From each 

 ovulation about five males and ten females are produced, 

 and if the reproduction were to. go on unhindered for three 

 months, the total reproduction would approximate 

 1,500,000 parasites. The adults are mere specks, barely 

 visible to the unaided eye. 



Swine become infested from infested premises or from 

 infested swine. Premises may remain infested for six 

 months or even longer. 



Lesions. The lesions produced by the Sarcoptes 

 are practically confined to the skin; however, secondary 

 lesions, as emaciation, may arise. The parasite obtains 

 tissue juice by pricking the skin with its stylet. The 

 stylet injury produces erythema, succeeded by the forma- 

 tion of vesicles, which rupture, the vesicular fluid drying 

 and forming a scab beneath which the parasites are 

 found. Scabs are of varying thickness, and accumulate 

 wherever the parasites are found unless the affected ani- 

 mal rubs them off. Galleries are formed within the skin, 

 and this also adds to the irritation. The accumulated 

 dry scabs break and damage the hair more or less, which 

 falls, leaving the parts affected practically hairless. The 

 irritation causes inflammation, and this results in fibrous 

 proliferation and thickening of the skin. The thickened, 

 leathery skin loses its pliability and becomes fissured or 

 cracked. In long-continued cases the animals become 

 emaciated. 



Symptoms. Intense pruritus, especially around the 

 ears and eyes, and the finding of papules, vesicles, and 

 scabs are the first evidences of scabies. Later there is 

 depilation and thickening of the skin, with the accompany- 

 ing rhagades. The disease will probably affect all the 



