526 VETEEINAEY HYGIENE 



them to return to their pasture. Should rain come on they 

 must remain in the dripping pen until it has ceased. These 

 precautions are mainly applicable to poisonous ' dips ' like 

 arsenic. Eain washes out the arsenic : in fact with all 

 dips the evil effects of rain are very evident, for one of the 

 objects aimed at is to leave sufficient material in the wool 

 to act as a preventive for some time to come.* 



A very practical point in connection with general dipping 

 is mentioned by Professor Wallace, and that is the subse- 

 quent difficulty of recognition between ewes and lambs. 

 The ewe recognises her offspring by its smell, but this is 

 destroyed by dipping. There is always some difficulty 

 in their mutual recognition after shearing, but all doubt 

 is removed by the sense of smell ; .after dipping the 

 distinctive smell is lost, and Wallace says competent 

 authorities estimate that in the case of large flocks running 

 wild in an upland country, probably one-third of the lambs 

 after dipping would never find their mothers. 



In dealing with an outbreak of scabies on a farm the 

 sheep are grouped according to degrees of severity, and in 

 this way in-contacts are separated from the affected. If 

 the time of year admits of shearing being done this should 

 be carried out, if not the bath must be used on the un- 

 shorn skin. In-contacts should first be dealt with, and 

 subsequently placed in a pen by themselves ; the other 

 groups may then be dipped in the order of severity, leaving 

 the worst cases until the last. By breaking up the flock 

 into groups not only is the supervision more effective, but 

 the spread of the disease is prevented. 



All rubbing places, posts, rails, etc., must be disinfected, 

 loose wool collected and burned, and the animals kept 

 penned until safe to mix with the healthy. Thorough dis- 

 infection of all hurdles used as pens must be observed. 

 One important point to attend to in curative measures is 



* The principle of a sheep bath may be gathered from the figure of 

 a cattle bath shown on p. 423. It should give 60 feet of actual swim, 

 so as to insure sufficient immersion. The depth of the bath to be 

 5i feet, the width 2 feet at the water-level, and 9 inches on the floor 

 of the bath. 



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