LICE AND MANGE 131 



first appears are the base of the tail, the neck, withers, 

 and shoulders. The skin becomes thickened and very 

 dry in places, the hair dropping off, leaving large bald 

 patches of thickened and callous skin. As the disease 

 progresses, there is an intense itching, and the animal will 

 be seen rubbing itself against fences, posts, buildings, 

 etc., sometimes causing large bleeding scratches and 

 sores. Animals in the advanced stages of the disease eat 

 very little, and spend the most of their time in rubbing. 

 The disease spreads very rapidly throughout a herd, and 

 appears in from four to six weeks after exposure. It 

 spreads by direct contactof diseased with healthy animals, 

 and railroad cars, stock-yards, mangers, sheds, posts, 

 chutes, and fences may also be sources of infection. 



The method of treatment advised is the application 

 by spraying or dipping, using a liquid that will kill the 

 parasites. In small herds the liquid may be applied 

 by means of a swab, brush, or spray pump, but even on 

 a small scale it is expensive and impracticable, and is 

 very likely not to be thoroughly done, as it is hard to 

 get the liquid into all the wrinkles and folds by this 

 method. The best plan is to dip in a properly con- 

 structed dipping vat, and this method is coming to be 

 the one most used especially in the great grazing sections, 

 where cooperative dipping plants are operated. 



There are numerous dips on the market, and no 

 doubt they all have their merits, but the ones found 

 to be most effective are the coal tar preparations, such 

 as Chloro-naphtholeum and Zenoleum. These should 

 ■ be used in a 3^ or 4 per cent solution, the latter being 

 preferred. In mixing the dips, soft water should be 

 used, and if this cannot be obtained, add to the hard 

 vater sufficient washing powder or soda to soften it, 

 otherwise the preparations will not thoroughly mix with 

 the water. 



Great care should be taken to make the dipping 

 thorough. A simple plunge in and out is not sufficient; 

 the cattle should be immersed from one to three minutes. 



