PARASITIC DISEASES OF THU SKIX. 257 



sheep infested with ticks, is a source of infection for the whole 

 flock. A sheep freed from ticks can only again become infected 

 with them by contact with other sheep harboring the parasite. 



Symptoms. 



The severity of the symptoms depends to a great extent on. 

 the number of parasites infesting the sheep. "While a few will 

 cause the animal but a trifling annoyance, in a short time they 

 increase to such numbers that they cause an intense irritation 

 and restlessness, interferring greatly with the well-being of the 

 sheep. Lambs particularly (owing to their tender skin) suffer 

 from these pests, being especially noticeable after shearing. 

 Animals harboring a large number of ticks will scratch and pull 

 the wool, the condition being easily differentiated from scab, 

 however, as a casual examination will reveal the ticks. 



Crcatment. 



The best method is to dip the whole flock, and the best time 

 is directly after shearing. One thorough dipping in any prepar- 

 ation used for scabies will be sufficient to destroy all the live 

 ticks, but as some of the nits are sure to be left in the fleece, it is 

 good policy to repeat the dipping in two or three weeks time. 



Sheep should not be turned into the old pastures until two 

 or three weeks after dipping. This allows a suflicient time for 

 the death of whatever ticks may have been dropped on the 

 ground. In fact it is a good plan to disinfect and clean out the 

 sheep-pens on the farm at least once l year. Many ticks will be 

 destroyed if this is carried out. Before introducing fresh mem- 

 bers to the flock they should always be dipped. This is a useful 

 precaution, and if taken will often prevent the spread of this class 

 of parasitic diseases. These parasites being easily destroyed, the 

 flock-owner should experience but slight difficulty in keeping his 

 sheep free of the same. 



