EXTERNAL PARASITES 241 



SCALY LEGS 



There is a common condition in some localities called scaly 

 legs, so called because the legs have accumulated upon them 

 scales or scabs. 



This is one form of scabies that is caused by a parasite be- 

 longing to the same family and genus as the one commonly 

 causing scabies or mange in the horse and dog. It is scientifi- 

 cally known as the Sarcopies mutans, variety gallince. It is 

 minute in size and scarcely larger than the point of a pin. 



Description. — ^The parasite infests the shanks or unfeathered 

 portion of the legs only — ^that is, from the hocks down to and 

 including the dorsal and lateral sides of the toes. The para- 

 site is oval in shape with mouth parts arranged for cutting 

 the skin. It lives on the serum that exudes from the injured 

 part. The parasites burrow between and gradually work their 

 way under the edge of the scale, where by their irritation a 

 small amount of serum exudes, which dries and which particle 

 contributes to the formation of a larger scab. The scaly leg 

 parasite multiplies by laying its eggs in galleries in the skin, 

 where they hatch out in the course of a few days, usually 

 about ten, into an asexual six-legged minute parasite. The 

 young parasite is practically invisible to the unaided eye. After 

 going through several molts it arrives at the fully developed 

 or adult state, and is now provided with reproductive organs 

 and eight pair of legs and ready to again repeat its Ufe cycle. 

 These scab parasites develop very fast in warm weather. By 

 increasing numbers and continuous irritation by their pres- 

 ence and biting, dried serum accumulates to such an extent 

 that the scales of the legs become forced up out of a normal 

 level. Finally, the legs appear with more or less large masses 

 of hard crusts or scales. By removing these scales it will be 

 noted that the undersurface is moist. In this moisture may 

 be observed minute hght-colored specks, almost pin-point in 

 size, and when removed by aid of the point of a needle or pin 

 and placed under a low-power magnifying lens they may be 

 noted to move about. 



■ These scab parasites, while they go through their entire life 

 cycle on the legs of the host, yet they will live for several days 

 off the host. 



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