PARASITIC DISEASES OF THE SKIN. 239 



ease progresses the scabby patches become confluent, thicker and 

 harder and white in appearance, extending over the lips, cheeks, 

 nostrils, face, forehead, eyes and ears in one hard, thick scabby 

 mass, causing an incessant, unbearable itching, in trying to allay 

 which, by rubbing and striking the part with its feet, the animal 

 tears through scab and skin, causing bleeding, soreness and ulcer- 

 ation of the part. As these patches increase round the edges, 

 the centers tend to heal, leaving scars and cicatrices to show the 

 ravages of the disease. "When the scabs cover the eyelids, the 

 animal is in danger of starving to death, being unable to see 

 where or how to obtain food. To find this insect it is necessary 

 to raise the scab and examine the moist underlying exudate by 

 the aid of a microscope. They are not to be found on the hard 

 and dry portions of the scab. 



Head scab is not a common form of the disease in Xorth 

 America, although cases of it are occasionally found. It is the 

 most susceptible to treatment of the three kinds of scab, and 

 while, unlike the common scab, it does not work direct injury to 

 the fleece If neglected, the patient becomes poor in flesh, and 

 indirectly by its effect on the general health, the normal growth 

 of the fleece is prevented, so curtailing the clip. 



■Crcatment. 



The application of a good sheep dip or wash will effectually 

 cure this trouble. 



Comnion Scab, psoroptcs Comtnunts. 



The parasite causing this disease is much larger than the 

 sarcoptes, being easily discernible with the naked eye, especially 

 if placed on a black surface. It has caused more monetary lo-s 

 to sheep breeders of all countries than any other condition or 

 disease, not excepting the ravages caused by the liver-fluke; so 

 rapidly does it run through a flock, and so destructive are its 



