THE SKIN 401 



attended to, and the bedding, which ought to be of pitch-pine 

 shavings or sawdust, changed every three or four days. Carbolic 

 acid, strong mercurial ointments, or tobacco wash, should never 

 be used on the dog, as these have a dangerously depressing and 

 sickening effect. Scab in sheep is an affection of the skin due to the 

 presence of small parasites, mites or acari, known as Dermatodectes 

 ovis, or Psoroptes communis, and developed from tiny eggs about 

 ^.i- part of an inch in length. The female parasite is intensely prolific, 

 lays its eggs and dies. It has been estimated that from the first to 

 the sixth generation, in about the space of ninety days, no less than 

 1,000,000 female and 500,000 male parasites are born. The com- 

 plaint is thus extremely contagious. The symptoms are great 

 uneasiness and itchiness of the parts, the sheep continually biting, 

 scratching with the hind-feet, and rubbing against posts or any 

 other object, tufts of wool become pulled out, and the sheep soon 

 have a ragged and dirty appearance. Both the remedy and 

 prevention is to dress the parts with some of the many sheep-dip 

 preparations approved of by the Board of Agriculture and Fisheries ; 

 dipping at intervals is also used as a preventive. The complaint is 

 scheduled under the Contagious Diseases (Animals) Act. 



681. Warbles {Plate XL. t 7, 5, 9). — These are small elevations 

 or tumours about the size of a lady's thimble, found on the backs of 

 cattle between the shoulders and loins. They may vary in number 

 up to fifty or more, and cause great loss, not only in the value 

 of the hides, but to the flesh immediately beneath as well. The 

 tumours contain larvae, developed from the eggs deposited by the 

 ovipositor of the female bot fly, or ox warble fly (Plate XL., 

 7, 8, 9), in the months of July and August, and they make their 

 appearance between the following February and May, or perhaps 

 later. According to the late Miss E. A. Ormerod, LL.D., the ox 

 warble fly ' is two-winged, and upwards of \ inch in length, and 

 is so marked that it resembles the humble-bee, with a yellowish 

 face, body between the wings, yellowish in front and black behind ; 

 abdomen whitish at the base, black at the middle, and orange at the 



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